NOVEL PARASITIC HELMINTH PROTEINS

Abstract: The present invention relates to isolated parasitic helminth nucleic acid sequences capable of hybridizing, under stringent conditions, to at least a portion of D. immitis nucleic acid sequence p4 and/or to at least a portion of D. immitis nucleic acid sequence p22U as well as to isolated nucleic acid sequences encoding P39, P22L or P20.5 or fragments thereof; to isolated parasitic helminth proteins that are encoded by such parasitic helminth nucleic acid sequences and that are capable of selectively binding to at least one component of immune serum capable of inhibiting helminth development; and to antibodies raised against such isolated parasitic helminth proteins. The present invention also relates to therapeutic compositions comprising such isolated nucleic acid sequences, proteins and/or antibodies. The present invention also includes methods to produce and use such nucleic acids, proteins, antibodies and therapeutic compositions capable of protecting animals from parasitic helminth infection and, particularly, from heartworm infection.

Description: NOVEL PARASITIC HELMINTH PROTEINS Field of the Invention The present invention relates to novel parasitic helminth proteins, nucleic acid sequences encoding such proteins and antibodies raised against such proteins. The present invention also includes a method to obtain such nucleic acid sequences and proteins, and a method of using such nucleic acid sequences, antibodies, and proteins to protect animals from infection. The present invention particularly relates to specific Dirofilaria immitis (D . immitis) nucleic acid sequences and proteins as well as their use to protect animals from heartworm infection. Background of the Invention Parasitic helminth infections in animals, including humans, are typically treated by chemical drugs, because there are essentially no efficacious vaccines available. One disadvantage with chemical drugs is that they must be administered often. For example, dogs susceptible to heartworm are typically treated monthly to maintain protective drug levels. Repeated administration of drugε to treat parasitic helminth infections, however, often leads to the development of resistant strains that no longer respond to treatment. Furthermore, many of the chemical drugs are harmful to the animals being treated, and as larger doses become required due to the build up of resistance, the side effects become even greater. It is particularly difficult to develop vaccines against parasitic helminth infections both because of the against parasitic helminth infections both because of the complexity of the parasite's life cycle and because, while administration of parasites or parasite antigens can lead to the production of a significant antibody response, the immune response is typically not sufficient to protect the animal against infection. As for most parasites, the life cycle of D . immitis , the helminth that causes heartworm, includes a variety of life forms, each of which presents different targets, and challenges, for immunization. Adult forms of the parasite are quite large and preferentially inhabit the heart and pulmonary arteries of an animal. Males worms are typically about 12 cm (centimeters) to about 20 cm long and about 0.7 mm to about 0.9 mm wide; female worms are about 25 cm to about 31 cm long and about 1.0 to about 1.3 mm wide. Sexually mature adults, after mating, produce microfilariae which are only about 300 μm (micrometers) long and about 7 μm wide. The microfilariae traverse capillary beds and circulate in the vascular system of the dog in concentrations of about 10 3 to about 10 5 microfilariae per ml of blood. One method of demonstrating infection in the dog is to detect the circulating microfilariae. If the dog is maintained in an insect-free environment, the life cycle of the parasite cannot progress. However, when microfilariae are ingested by the female mosquito during blood feeding on an infected dog, subsequent development of the microfilariae into larvae occurs in the mosquito. The microfilariae go through two larval stages (LI and L2) and finally become mature third stage larvae (L3) of about 1.1 mm length, which can then be transmitted back to the dog through the bite of the mosquito. It is this L3 stage, therefore, that accounts for the initial infection. As early as three days after infection, the L3 molt to the fourth larval (L4) stage, and subsequently to the fifth stage, or immature adults. The immature adults migrate to the heart and pulmonary arteries, where they mature and reproduce, thus producing the microfilariae in the blood. "Occult" infection with heartworm in dogs is defined as that wherein no microfilariae can be detected, but the existence of the adult heartworms can be determined through thoracic examination. Heartworm not only is a major problem in dogs, which typically cannot even develop immunity upon infection (i.e., dogs can become reinfected even after being cured by chemotherapy) , but is also becoming increasingly widespread in other companion animals, such as cats and ferrets. Heartworm infections have also been reported in humans. Other parasitic helminthic infections are also widespread, and all require better treatment, including a preventative vaccine program. Although many investigators have tried to develop vaccines based on specific antigens, it is well understood that the ability of an antigen to stimulate antibody production does not necessarily correlate with the ability of the antigen to stimulate an immune response capable of protecting an animal from infection, particularly in the case of parasitic helminths. A large number of materials are immunogenic and produce sera which test positive in immunoassays for ability to react with the immunizing antigen, but which fail to protect the hosts against infection. Antibodies which neutralize the infective agent in in vitro assays are much more likely to protect against challenge in vivo . Accordingly, the use of serum simply resulting from immunization or from infection by a parasitic helminth to screen for candidate vaccines does not provide sufficient specificity to identify protective immunogens. On the other hand, serum or other components of blood from immunized animals which is demonstrably protective against infection would contain antibodies, cells, or other factors that could selectively bind to potential antigens that, if used as therapeutic compositions, would elicit immune responses that protect against challenge. In most infectious diseases, particularly those such as parasitic infections that have long and complex development courses, it is difficult to verify the protective effect of serum or T-cells from exposed animals for use as a screening reagent. First, verification of protection against challenge is tedious, since the host animal would first have to be challenged with the infectious agent and shown to be protected before it could be shown that antibody components of serum, for example, could be used as a screen. The definition of protection under such a regimen is often complex. Second, even if a protective effect against challenge is shown, it is not clear to what components of the immune system the protection is due. The protective effect could be due to antibodies, cells, mediators of the immune system or to combinations thereof. Thus, although this method of obtaining the screening reagent is sometimes used, it iε time-consuming and does not permit identification of protective components. A method to determine the effectiveness of in vivo immunization protocols includeε implanting diffusion chambers containing infectious agents into immunized animals and determining the effects of such immunizations on the implanted infectious agents. Grieve, et al., 1988, Am. J. Trop. Med . Hyg. 39, p. 373-379, for example, report that dogs which had been immunized against D . immitis infection were supplied diffusion chambers containing infective larvae. The larvae in the chambers could then be evaluated for the effect of the previous immunizations. Abraham, et al., 1988 J. Paraεit . 74, p. 275-282, report that mice which had been immunized with L3 were supplied diffusion chambers containing D . immitis third-stage larvae, and the effects on these larvae were used to determine the possible immunity of the mice putatively developed by such immunization. Thus, the papers disclose that implantation of diffusion chambers containing the infectious agent into an immunized animal provides a convenient assessment of the effectiveness of certain directly administered active immunization protocols, but do not describe the use of such chambers to monitor passively transferred protective effects of selected fractions of a target host bloodstream. Protection against parasitic helminth infections is difficult to achieve because, as heretofore stated, the complexity of the parasitic infection makes the choice of a candidate immunogen for vaccination very difficult. Even naturally conferred immunity cannot be assured to exist, as dogs with previous or existing infections with D . immitis can be reinfected (see, for example, Grieve et al., 1983, Epidemiologic Reviews 5, p. 220-246) . However, this review also reports that there is some evidence of a naturally occurring protective immune response, which apparently limits the population of mature worms in infected dogs. Furthermore, it has been possible to induce protective immunity artificially. Wong, et al., 1974, Exp . Paras itol . 35, p. 465-474, reported the immunization of dogs with radiation-attenuated infective larvae. The dogs were protected to varying degrees upon challenge. Blair, et al., 1982 in Fifth International Congress of Paras itology , Toronto, Canada, reported successful immunization by infecting the dogs and terminating the infection at the fourth larval stage by chemotherapy. Grieve, 1989, Proc . Heartworm Symp. , p. 187-190, reviewed the status of attempts to produce vaccines against heartworm in dogs. Thiε report summarizes the use of infective larvae implanted in an inert diffusion chamber which permits the influx of cells and/or serum from the host and outflow of parasite material from the chamber to assess the effectivenesε of inoculation protocolε in both dogs and mice. The use of immunization with infective larvae was demonstrated to be partially effective in protection against subsequent challenge. An alternative approach to finding, for example, a heartworm vaccine has been to attempt to identify prominent antigens in the infective stage of D . immitis . Philipp, et al., 1986, J. Immunol . 136, p. 2621-2627, reports a 35- kilodalton (kD) major surface antigen of D . immitis third stage larvae which was capable of immunoprecipitation with sera from dogs carrying an occult experimental D . immitis infection or with sera from dogs immunized by irradiated third stage larvae. In addition, this group reported (Davis, et al., 1988, Abstract 404, 37th Annual Meeting, Am. Soc . Trop. Med . Hyg. ) three major surface proteins of the L4 having molecular weights of 150 kD, 52 kD, and 25 kD. The 25 kD molecule seemed unique to L4 larvae. Ibrahim, et al., 1989, Paras itol . 99, p. 89-97, using D . immitis L3 larvae labeled with 15 I, showed that a 35 kD and 6 kD component were shed into the culture medium by developing parasites. They further showed that antibodies from immunized rabbits and infected dogs immunoprecipitated the 35 kD, but not the 6 kD, component. Scott, et al, 1990, Acta Tropica 47, p. 339-353, reported characterization of the surface-associated molecules of D . immitis L2, L3, and L4 by radiolabeling techniques and SDS-PAGE (sodium dodecyl sulfate polyacrylamide gel electrophoresiε) . They found major labeled components of 35 kD and 6 kD in extracts from iodine-labeled L2 and L3; lactoperoxidase-catalyzed labeling revealed components of apparent molecular weights 66 kD, 48 kD, 25 kD, 16.5 kD, and 12 kD. Iodine labeling of surface-associated molecules of L4 gave molecules of apparent molecular weights of 57 kD, 40 kD, 25 kD, 12 kD, and 10 kD; lactoperoxidase-catalyzed labeling showed additional bands of 45 kD, 43 kD, and 3 kD. However, these antigens were identified using uncharacterized serum sources. Other approaches to obtaining vaccines against parasites in general have focused on the production of neutralizing antibodies. For example, both in vitro studies by Tanner, et al., 1981, Trans . Roy . Soc . Trop . Med . Hyg . 75, p. 173-174 and by Sim et al. , 1982, Trans . Roy . Soc . Trop. Med . Hyg . 76, p. 362-370, and in vivo studies by Parab et al., 1988, Immunol . 64, p. 169-174, have demonstrated that antibodies are effective alone or with other immune components in killing filarial L3 from Dipetalonema (Acanthocheilonema) viteae or JBrugria malayi . Furthermore, passive immunity to Schistosoma mansoni has been transferred from immune rats or humans to normal mice (see, for example, Sher, et al., 1975, Paraεitol . 70, p. 347-357; Jwo et al. , 1989, Am. J . Trop . Med . Hyg . 41, p. 553-562) . None of these studies involved the use of an in vivo assay to determine the ability of serum, or cellular, components to be a useful screening tool for identifying protective antigens. Neither haε any of theεe εtudieε yet identified an effective vaccine. Summary of the Invention The present invention includes an isolated parasitic helminth nucleic acid sequence capable of hybridizing, under stringent conditions, to at least a portion of D . immitis nucleic acid sequence p4 and/or to at least a portion of D. immitis nucleic acid sequence p22U. A preferred isolated nucleic acid sequence encodes a protein capable of selectively binding to at least one component of immune serum that is capable of inhibiting helminth development. Another preferred nucleic acid sequence includes an oligonucleotide capable of hybridizing to at least one of the D . immitis nucleic acid sequences under stringent hybridization conditions. The present invention also includes recombinant molecules and recombinant cellε that include isolated nucleic acids of the present invention. Also included is a method to produce isolated nucleic acid sequences of the present invention. Another embodiment of the present invention includes an isolated parasitic helminth protein, or mimetope thereof, capable of selectively binding to at least one component of immune serum that is capable of inhibiting helminth development, the protein being encoded by a parasitic helminth nucleic acid sequence capable of hybridizing, under stringent conditions, to at least a portion of D. immitis nucleic acid sequence p4 and/or to at least a portion of D . immitis nucleic acid sequence p22U. Preferred immune serum is derived from an animal that is immune to infection by the helminth, and preferably from an animal immunized with third stage and/or fourth stage larvae. Also included is a method to produce such isolated proteins and mimetopes of the present invention. Yet another embodiment of the present invention is an antibody capable of selectively binding to a parasitic helminth protein or mimetope thereof, the antibody being produced by a method that includes administering to an animal an effective amount of an isolated protein or mimetope of the present invention. Also included iε a method to produce such antibodies. Yet another embodiment of the present invention is a therapeutic composition capable of protecting an animal from parasitic helminth infection when administered to the animal in an effective manner. The therapeutic composition includes at least one of the following therapeutic compounds: an isolated nucleic acid sequence of the present invention, an isolated protein or mimetope of the present invention, and/or an antibody of the present invention. The composition can also include an excipient, adjuvant, and/or carrier. Preferably, the therapeutic compoεition protects the animal against heartworm. The present invention also includes a method to protect an animal from parasitic helminth infection by administering such therapeutic compositions. Yet another embodiment of the present invention includes a therapeutic compoεition capable of protecting an animal from paraεitic helminth infection when administered to the animal in an effective manner, the composition including a compound capable of substantially interfering with the function of a parasitic helminth LDL receptor- related protein class A cysteine-rich motif. A preferred therapeutic composition is a protein encoded by an isolated nucleic acid sequence capable of hybridizing, under stringent conditions, to at least a portion of D . immitis nucleic acid sequence p4. The present invention also includes a method to protect animals from parasitic helminth infection using such therapeutic compositions. Preferred parasitic helminths of the present invention include nematodes, cestodes and trematodes, with filarial, ascarid, strongyle and trichostrongyle nematodes being more preferred. Dirofilaria , Onchocerca , Brugia , Wuchereria , Loa , Acanthocheilonema , Dipetalonema , Setaria , Parafilaria and Stephanofilaria filarial nematodes are even more preferred, and D . immitis , the parasite that causes heartworm, is even more preferred. The present invention also includes a biologically pure protein which can be isolated from the L3 or L4 larval stage of a nematode parasitic in mammalε, or a fragment of such a protein, the protein or fragment thereof being immunoreactive with a component validated as protective in an immune host. The biologically pure protein is further characterized by being one of the following: (a) a P39 protein having a molecular weight of about 39 kD as meaεured by Tris-glycine SDS-PAGE; (b) a P22L protein having a molecular weight of about 22 kD as measured by Tris-glycine SDS-PAGE and a molecular weight of about 19 kD measured by Tris-tricine SDS-PAGE; and (c) a P20.5 protein having a molecular weight of about 20.5 kD as measured by Tris-glycine SDS-PAGE and a molecular weight of about 16 kD as measured by Tris-tricine SDS-PAGE. Preferably the nematode is a filarial nematode, more preferably D . immitis . One embodiment of the present invention are antibodies immunoreactive with such proteins. The present invention also includes nucleic acid sequences encoding P39, P22L and/or P20.5 proteins or fragments thereof, having the aforementioned characteristics. Also included are oligonucleotides complementary to at least a portion of such nucleic acid sequences. Also included are recombinant vectors comprising at least a portion of at least one of such nucleic acid sequences. Another embodiment of the preεent invention is a recombinant expression system capable of producing at least one of the aforementioned proteinε, the εystem comprising a nucleic acid sequence encoding the protein operably linked to at leaεt one control sequence. Also include in the present invention is a recombinant host cell containing such a recombinant expression system. One aspect of the present invention is a method to produce a P39, P22L and/or P20.5 protein or fragment thereof having the characteristicε heretofore disclosed, the method including (a) culturing recombinant host cellε capable of producing such a protein under conditions compatible with expression, and (b) recovering the protein or fragment from the culture. Also included are proteins produced by such a method. The present invention also includes a pharmaceutical composition useful for immunizing a susceptible mammalian host against a parasitic nematode, the composition comprising a P39, P22L and/or P20.5 protein or fragment thereof (as heretofore characterized) in admixture with a suitable pharmaceutically acceptable excipient as well as a method to immunize a mammalian host against a parasitic nematode, the method including administering to the host an effective amount of the protein, fragment or pharmaceutical composition thereof. Preferably the nematode is a filarial nematode. More preferably the nematode is D . immitis and the host is canine. Another aspect of the present invention iε a pharmaceutical composition for use in immunizing a mammalian host against a parasitic nematode, the composition comprising a recombinant expresεion εystem aε heretofore disclosed in admixture with a pharmaceutically acceptable excipient. Also included is a method to immunize a mammalian host against a paraεitic nematode, the method including administering to the host an effective amount of the expression system or a pharmaceutical composition thereof. Brief Deεcription of the Figures FIG. 1 depictε a chromatogram of the separation of larval ES by cation exchange chromatography. FIG. 2 depicts a chromatogram of the separation of tryptic fragments of P22U by C 18 reverse phase chromatography; P22U was purified by cation exchange and C 4 reverse phase chromatography. FIG. 3 shows the hydrophilicity plot and protein characteristicε calculated for the sequences of the P20.5 (also referred to aε 20 kD) and P22L (also referred to as 22L kD) proteins. Detailed Description of the Invention The present invention includes isolated parasitic helminth proteins and mimetopes thereof that are capable of selectively binding to at least one component of a serum collected from an animal that is immune to infection by the helminth, the serum being capable of inhibiting helminth development; that is, the protein is immunoreactive with a component validated as protective in an immune host using, for example, the method disclosed in Grieve et al., PCT International Publication No. WO 92/13560, published August 20, 1992. The ability of εuch proteins and mimetopes to selectively bind to components in such a serum iε believed to suggest the ability of such proteins and mimetopeε to protect an animal from parasite infection when such proteins and/or mimetopes are administered to an animal in an effective manner. Animals that are immune to infection by parasitic helminths are animals that exhibit an immune responεe that is sufficient to protect the animal from such infection. Immune animals typically are animals that have been administered larval, adult and/or microfilarial helminths in a manner effective to elicit a protective response, preferably using irradiated helminths or a chemically- abbreviated infection protocol. For example, dogs receiving chemically abbreviated D . immitis larval infections exhibit significant immunity to challenge infections. Furthermore, sera obtained from such dogs are effective in passively transferring larval killing and stunting capabilities to mice. Preferred immune animals are those that have been immunized against helminth larvae, particularly against L3 and/or L4 larvae, since, in accordance with the present invention, it is particularly desirable to prevent L3 larvae introduced into an animal from developing into adult parasites. It should be noted, however, that immune animals do not preclude naturally- infected animals that generate protective antibodies. According to the present invention, an isolated, or biologically pure, parasitic helminth protein, is a protein that has been removed from its natural milieu. As such, "isolated" and "biologically pure" do not necesεarily reflect the extent to which the protein haε been purified. An isolated parasitic helminth protein can be obtained from its natural source. Alternatively, the isolated parasitic helminth protein can be produced using recombinant DNA technology or chemical εynthesis. Isolated proteins include full-length proteins as well as modified versions of the protein in which amino acidε have been deleted (e.g., a truncated verεion of the protein, such as a peptide) , inserted, inverted, substituted and/or derivatized (e.g. , glycosylated, phosphorylated, acetylated) such that the modified version of the protein has a biological function substantially similar to that of the natural protein (i.e., functionally equivalent to the natural protein) . Modifications can be accomplished by techniques known in the art including, but not limited to, direct modifications to the protein or modifications to the gene encoding the protein using, for example, clasεic or recombinant DNA techniqueε to effect random or targeted mutagenesiε. Isolated proteins of the present invention, including modified versions thereof, can be identified in a straight-forward manner by the proteins' ability to selectively bind to at least one component of anti- parasitic helminth immune serum. As used herein, immune serum refers to serum that is capable of inhibiting helminth development that preferably is derived (e.g., obtained from) an animal that is immune to the helminth. The minimum size of isolated proteins of the present invention is sufficient to form an epitope, a size that is typically at least about 7 to about 9 amino acids. As is appreciated by those skilled in the art, an epitope can include amino acids that naturally are contiguous to each other as well as amino acids that, due to the tertiary structure of the natural protein, are in sufficiently close proximity to form an epitope. In accordance with the present invention, a mimetope refers to any compound that is able to mimic the ability of an isolated protein of the present invention to selectively bind to at least one component of anti-parasitic helminth immune serum. A mimetope can be a peptide that has been modified to decrease its susceptibility to degradation but that still retains its selective binding ability. Other examples of mimetopes include, but are not limited to, anti-idiotypic antibodies, or fragments thereof, that include at least one binding site that mimics one or more epitopes of an isolated protein; non-proteinaceouε immunogenic portions of an iεolated protein (e.g., carbohydrate structures) ; and synthetic or natural organic molecules, including nucleic acids, that have a structure similar to at least one epitope of an isolated protein of the present invention. Such mimetopes can be obtained, for example, by affinity chromatography techniques using immune sera of the present invention or antibodies raised against isolated proteins of the present invention. As used herein, the term "selectively binds to" refers to the ability of isolated proteins and mimetopes thereof to bind to serum collected from animals that have been exposed to parasitic helminths (either through natural infection or through administration of helminthε) but essentially not to bind, according to standard detection techniques (such as those described in Sambrook et al., Molecular Cloning: A Laboratory Manual , Cold Spring Harbor Labs Press, 1989) to serum collected from animals that have not been exposed to parasitic helminths (i.e., naive animals) . Preferably, the isolated proteins and mimetopes are able to bind to anti-parasitic helminth immune serum with high affinity. The ability of a protein or mimetope thereof to selectively bind to anti-parasitic helminth immune serum can be measured using a variety of methods known to those skilled in the art including immunoblot assays, immunoprecipitation assays, enzyme immunoassayε (e.g., ELISA), radioimmunoassayε, immunofluorescent antibody asεayε and immunoelectron microεcopy. It εhould be noted that the ability of an isolated protein or mimetope thereof to selectively bind to immune serum raised against a certain stage of helminth development does not preclude the isolated protein or mimetope from being able to also bind to immune serum raised against other stages of helminth development. For example, the ability of an isolated protein or mimetope thereof to selectively bind to an anti-larval immune serum doeε not preclude the isolated protein or mimetope from being able to also bind to anti- microfilarial and/or anti-adult immune serum. As used herein, the phrases "capable of selectively binding to at least one component of a serum collected from an animal that is immune to infection by the helminth, the serum being capable of inhibiting helminth development" and "specifically immunoreactive with validated components of immune host serum or tissue" have similar meanings. "Validated components" are components which have been shown in the method of the invention, as described herein, to exert a deleterious effect on the parasitic nematodes when supplied in a diffusion chamber to a neutral host which has been administered the component. By "specifically immunoreactive" is meant that the immunogen is capable of binding the validated component as derived from an immune susceptible host, but is incapable of binding components found in nonimmune counterparts in this species. By "susceptible host" is meant a hoεt εpecies that iε ordinarily susceptible to infestation by the nematode parasite in question. Individual members of the susceptible host species may have acquired immunity to this infestation. One embodiment of the present invention iε the uεe of anti-parasitic helminth immune serum to identify isolated proteins and mimetopes of the present invention, a technique referred to herein as immune serum screening assay. Immune serum can be raised against a parasitic helminth by administering the helminth to an animal under conditions that elicit an immune responεe. Immune serum can be raised against larval, microfilarial, and/or adult helminths, preferably against larvae, and more preferably against L3 and/or L4 larvae. Immune sera of the present invention are capable not only of inhibiting development of the species of helminth that elicited the immune response, but also of helminth species that immunologically cross- react with the immune sera. Due to the similarity between helminths, immune sera of the present invention are capable of reacting with a large variety of helminths. Inhibiting the development of helminths includes killing, reducing the growth of, blocking the maturation of, altering the morphology of, altering the metaboliεm of, and/or otherwise being detrimental to the helminth. Any animal that is capable of mounting an immune response to protect itself from helminth infection is a suitable animal to which helminths can be administered and from which immune serum can be collected. For example, a preferred animal from which to collect serum capable of inhibiting the development of D . immitis is a dog that haε been administered L3 and/or L4 D . immitis larvae under conditions that elicit an immune response. The ability of immune serum of the present invention to inhibit parasitic helminth development can be determined in a number of wayε. A preferred method to monitor the ability of immune serum to inhibit the development of an infectious agent is disclosed by Grieve et al., WO 92/13560, ibid . As disclosed therein, for example, the ability of an anti-parasitic helminth larval immune serum to inhibit larval development can be determined as follows. Briefly, a naive animal (i.e., an animal not previously exposed to parasitic helminth larvae) is implanted with at least one diffusion chamber containing helminth larvae, preferably L3 larvae. The animal is also administered either the anti-larval immune serum to be teεted or a control non-immune serum, preferably at a site near the diffusion chambers. After a suitable period of time, for example, from about three to about four weeks for D . immitis larvae implanted in mice, the diffusion chambers are removed, and the effects of the immune serum on larval growth and development are determined by, for example, comparing larval growth and survival in chambers exposed to anti-larval immune serum with the growth and survival of larvae in diffusion chambers exposed to non-immune serum. A significant number of larvae exposed to anti-larval immune serum are either killed or stunted compared to larvae exposed to non-immune serum. Grieve et al., WO 92/13560, ibid . , further discloses use of the immune serum screening assay to screen for, and hence identify, desired proteins that selectively bind to the immune serum. Briefly, the immune serum can be contacted with a protein-containing composition under conditions that permit selective binding by desired proteins to componentε in the serum. Complexes between the proteins and serum components are recovered, the proteins are separated from the serum components and are then analyzed. Nucleic acid sequence encoding such proteins can be identified using known recombinant DNA techniques, such as those described in Sambrook et al. , ibid . In another embodiment, the immune serum screening assay can be used to identify nucleic acid sequenceε encoding isolated proteins of the present invention by screening parasite helminth expression cDNA libraries with immune sera of the present invention to identify proteins expressed by individual cloneε that are capable of εelectively binding to the immune sera. The immune serum screening assay can also be used to identify mimetopes capable of selectively binding to immune serum, such as to anti-L3 and/or L4 larval immune serum. Mimetopes can also be designed or improved using information derived from proteins identified by the immune serum screening assay. It should be appreciated that not only serum, but also other immunogenic components of bodily fluids collected from animals immune to helminth infection, such as cells, specific antibodies, and fragments thereof, can be used in the immune serum screening assay. As disclosed in Grieve et al. , WO 92/13560, ibid . , anti-larval immune serum has been used to identify nematode proteins expressed during L3 and/or L4 that have molecular weights of 66 kD, 65 kD, 59 kD, 39 kD, 33 kD, 23/24 kD, 22/20.5 kD and 14 kD, as determined by their migration patterns when submitted to Tris-glycine SDS PAGE. Nucleic acid sequences encoding these proteins can be identified using anti-L3 and/or L4 larval immune serum to screen larval nematode cDNA expression libraries. One embodiment of the present invention is an isolated parasitic helminth nucleic acid sequence that encodes an isolated protein of the present invention. As used herein, an isolated parasitic helminth nucleic acid εequence is a nucleic acid sequence that has been removed from its natural milieu. As such, "isolated" does not reflect the extent to which the nucleic acid sequence has been purified. An isolated nucleic acid sequence can be DNA, RNA, or derivatives of either DNA or RNA. Isolated nucleic acid sequences of the present invention include sequences that encode at least one epitope capable of selectively binding to immune sera of the present invention as well as oligonucleotideε that can function in a variety of ways, including, but not limited to, as probes, primers, and therapeutic agents using, for example, antisense-, triplex formation- and/or ribozyme-based technologies. An isolated parasitic helminth nucleic acid sequence can be obtained from its natural source either as an entire gene or a portion thereof, the minimal size of a portion being a εize that can form a stable hybrid with a similar nucleic acid sequence under stringent conditions. Aε such, isolated nucleic acid sequences can include regulatory regions that control expression of the corresponding coding region (e.g. , transcription or translation control regions or control sequences) , full-length or partial coding regions, and combinations thereof. Isolated parasitic helminth nucleic acid sequences can also be produced using recombinant DNA technology (e.g., PCR amplification, cloning) or chemical synthesis. Isolated parasitic helminth nucleic acid sequences include functional equivalents of natural sequences, including, but not limited to, natural allelic variants and modified nucleic acid sequences in which nucleotides have been inserted, deleted, substituted, and/or inverted in such a manner that such modifications do not substantially interfere with the nucleic acid sequence's ability to encode an epitope recognized by immune sera of the present invention or do not substantially interfere with the ability of the nucleic acid sequence to form stable hybrids under stringent conditions with natural isolates. As used herein, stringent hybridization conditions refer to standard hybridization conditions under which nucleic acid sequences, including oligonucleotides, are used to identify similar sequences. Such standard conditions are disclosed, for example, in Sambrook et al., iJid. Examples of such conditions are provided in the Examples εection. Functionally equivalent nucleic acid sequences can be obtained using methods known to those skilled in the art (see, for example, Sambrook et al., ibid . ) . For example, nucleic acid sequences can be modified using a variety of techniques including, but not limited to, classic mutagenesis techniques and recombinant DNA techniques, such as site-directed mutagenesis, chemical treatment of a nucleic acid to induce mutations, restriction enzyme cleavage of a nucleic acid fragment, ligation of nucleic acid fragments, polymerase chain reaction (PCR) amplification and/or mutagenesis of selected regionε of a nucleic acid sequence, synthesis of oligonucleotide mixtures and ligation of mixture groups to "build" a mixture of nucleic acid sequences, and combinations thereof. Functionally equivalent nucleic acids can be selected from a mixture of modified nucleic acid sequences by screening for the function of the protein encoded by the nucleic acid sequence (e.g., ability to bind to immune serum) and/or by hybridization with natural nucleic acid sequences under stringent conditions. Due to the similarity between parasitic helminth genomes, isolated proteins and corresponding nucleic acid sequences of the present invention can be from any parasitic helminth. Preferred helminths include nematode, cestode and trematode parasites. More preferred helminths include filarial, ascarid, strongyle and trichostrongyle nematodeε. Even more preferred helminthε include Dirofilaria, Onchocerca , Brugia , Wuchereria , Loa , Acanthocheilonema , Dipetalonema , Setaria , Parafilaria and Stephanofilaria filarial nematodeε. A particularly preferred parasitic helminth of the present invention is D . immitis , the filarial nematode that causes heartworm. Other suitable parasitic nematodes include Dipetalonema perstanε , Dipetalonema εtreptocerca, Wuchereria bancrofti , B . malayi , Mansonella ozzardi , Loa loa , O. volvulus, Strongyloides εpp. , Strongyluε εpp. , Haemonchuε spp. , Trichoεtrongylus εpp. , Oεtertagia spp. , Cooperia spp. , Dictyocauluε spp. , Nematodiruε εpp. , Cyathostominae (small strongyles of horses) , Oeεophagoεtomum εpp. , Chabertia ovina , Ancyloεtoma εpp. , ϋncinaria spp. , Bunoεtomum εpp. , Filaroideε εpp. , Aeluroεtrongyluε abstruεus, those nematodes of the order Ascaridida (Ascarids) , Trichinella εpiraliε, Trichuriε spp. , Angioεtrongyluε εpp. and Enterobiuε vermicular iε . One embodiment of the present invention is an isolated parasitic helminth nucleic acid sequence that is capable of hybridizing, under stringent conditions, to at leaεt a portion of D . immitis nucleic acid sequence p4. A protein encoded by such a nucleic acid sequence is preferably capable of selectively binding to at least one component of anti-parasitic helminth immune serum, and more preferably to anti-L3 and/or L4 larval immune serum. D . immitis nucleic acid sequence p4, also referred to as D . immitis p4, is a nucleic acid sequence of about 913 nucleotideε in length that haε been iεolated from a D . immitis L3 and/or L4 cDNA expreεεion library using immune serum collected from a dog that was immunized by repeated chemically abbreviated infectionε (e.g., infect with about 200 L3, wait about 60 dayε, treat with ivermectin, wait about 60 days, reinfect, etc.). Genomic sequences including p4 coding sequences also apparently include about 710 nucleotideε comprising one or more introns. Sequencing of D . immitis p4 cDNA has resulted in the nucleic acid sequence disclosed in SEQ ID NO:l. It should be noted that sequencing technology is not entirely error- free and that SEQ ID N0:1, aε such, represents an apparent nucleic acid sequence of D . immitis p4. The deduced translation of SEQ ID NO:l, repreεented in SEQ ID NO:2, suggests that D. immitis p4 compriseε an open reading frame of about 303 amino acids and, as εuch, represents only a portion of the entire coding sequence of the gene. The nucleic acid contained in D . immitis p4, however, iε sufficient to encode a protein that selectively binds with anti-D. immitis larval immune serum, as demonstrated by the manner in which the nucleic acid sequence was isolated. The deduced translation of SEQ ID N0:1 suggestε that the protein encoded by D . immitis p4 has a molecular weight of about 35.5 kilodaltons (kD) and an estimated pi of 4.26. The protein encoded by D. immitis p4 is further characterized by having an LDL receptor-related protein (LDLr) class A cysteine-rich motif of about 9 amino acids that iε also found in several other proteins, including mammalian low density lipoprotein (LDL) receptors, LDL receptor-related proteins, human and mouse alpha-2- macroglobulin receptors and rat renal GP 330 glycoprotein. Each of these proteinε, including D . immitis P4, share the sequence DDCGDGSDE (i.e., Aspartic Acid — Aspartic Acid — Cysteine — Glycine — Aspartic Acid — Glycine — Serine - - Aspartic Acid — Glutamic Acid) . A conserved stretch of eight of the nine amino acids is also found in the free- living (i.e., non-parasitic) nematode Caenorhabditis eleganε LDL receptor-related protein and C . eleganε basement membrane proteoglycan. This LDLr class A, cysteine-rich motif is likely to be conserved in proteins encoded by p4-related sequences of other helminths (i.e., nucleic acid sequences that hybridize under stringent conditions with D . immitis p4) . As such, p4-related nucleic acid sequences may be identified using oligonucleotide probes that encode such LDLr clasε A motifs. Furthermore, the LDLr class A motif in P4-related proteins represents a target for development of therapeutic compositions to protect animals from parasitic helminth infection, as diεcuεεed below. The present invention includes nucleic acid sequences from any parasitic helminth that hybridize under stringent conditions to at least a portion of D . immitis nucleic acid sequence p4, the minimal size of the portion being defined by the hybridization conditions. Due to the similarities between parasitic helminths, as heretofore disclosed, one can use D . immitis p4 εequences to obtain other paraεitic helminth nucleic acid εequences that are capable of hybridizing, under εtringent conditions, to at leaεt a portion of D . immitis p4. Preferred helminthε are heretofore disclosed. Particularly preferred nucleic acid sequenceε of the present invention include D . immitis nucleic acid sequence p4, nucleic acid sequences including D . immitis p4, and nucleic acid sequence comprising fragments of D . immitis p4 (including functional equivalentε of any of these nucleic acid sequences) . Knowing the sequence of D . immitis p4 allows one skilled in the art to make copies of the sequence as well as to obtain nucleic acid sequenceε including D . immitis p4 and nucleic acid εequenceε that contain fragments of D. immitiε p . As such, particularly preferred isolated nucleic acid sequenceε include SEQ ID N0:1 or a functional equivalent thereof, a nucleic acid sequence containing at least a portion of SEQ ID N0:1 or a functional equivalent thereof, and a fragment of SEQ ID N0:1 or a functional equivalent thereof, assuming the accuracy of SEQ ID N0:1. The present invention also includes an isolated parasitic helminth protein that is encoded, at least in part, by a parasitic helminth nucleic acid sequence capable of hybridizing, under stringent conditions, to at least a portion of D . immitiε nucleic acid sequence p4, as well as mimetopes of such a protein. Preferably, the protein or mimetope thereof is also capable of selectively binding to at least one component of anti-parasitic helminth immune serum, and more preferably to anti-L3 and/or L4 larval immune serum. Preferred isolated parasitic helminth proteins or mimetopes thereof are capable of protecting an animal from helminth infection when administered to the animal in an effective manner. Preferred helminths are heretofore disclosed. Particularly preferred isolated proteins include proteins encoded by D . immitis nucleic acid sequence p4, a nucleic acid sequence including D . immitis p4, or a nucleic acid sequence comprising a fragment of D . immitiε p4. As such, particularly preferred isolated proteins are those encoded by SEQ ID NO:l or a functional equivalent thereof, a nucleic acid sequence containing at least a portion of SEQ ID N0:1 or a functional equivalent thereof, and a fragment of SEQ ID N0:1 or a functional equivalent thereof, as well as proteins that contain at leaεt a portion of SEQ ID NO:2, aεεuming the accuracy of SEQ ID NO:l and SEQ ID NO:2. One embodiment of the present invention is an isolated parasitic helminth nucleic acid sequence that is capable of hybridizing, under stringent conditions, to at least a portion of D . immitis nucleic acid sequence p22U. A protein encoded by such a nucleic acid εequence is preferably capable of εelectively binding to at least one component of anti-parasitic helminth immune serum, and more preferably to anti-L3 and/or L4 larval immune serum. D . immitis nucleic acid sequence p22U, also referred to as D . immitis p22U, encodes at leaεt a substantial portion of a basic D . immitiε protein, referred to as D . immitiε P22U protein, that migrates at an apparent molecular weight of about 22 kD when submitted to Tris-glycine SDS (sodium dodecyl sulfate) PAGE (polyacrylamide gel electrophoresis) . D . immitiε P22U protein has been identified in larval ES (excretory-secretory) extracts as well as in extracts of L3, L4 and adults. D . immitiε p22U is about 1016 nucleotides in length. Sequencing of D . immitiε p22U has resulted in the nucleic acid sequence disclosed in SEQ ID NO:3. It should be noted that sequencing technology is not entirely error-free and that SEQ ID NO:3, as such, represents an apparent nucleic acid sequence of D . immitiε p22U. The deduced translation of SEQ ID NO:3, represented in SEQ ID NO:4, suggests that D . immitiε p22U includes an open reading frame of about 208 amino acids followed by a stop codon. The translation start site is aε yet unknown although there are two "in-frame" potential εtart codonε at about amino acid 13 and about amino acid 19 of corresponding (i.e., deduced) amino acid sequence SEQ ID NO:4. The deduced amino acid sequence suggests a protein having a molecular weight of about 22 kD and an estimated pi of about 9. 6. D . immitiε p22U can be iεolated in a number of ways including, but not limited to, εcreening an L3, L4, or adult expression cDNA library with appropriate immune serum or with antibodies raised against D . immitiε P22U protein. Alternatively, amino acid sequence information can be derived from purified D. immitiε P22U protein that can be used to design oligonucleotide probes and/or primers that can be used to screen and/or amplify sequences from an appropriate cDNA or genomic library. The present invention includes nucleic acid sequences from any parasitic helminth that hybridize under stringent conditions to at least a portion of D . immitiε nucleic acid sequence p22U, the minimal size of the portion being defined by the hybridization conditions. Due to the similarities between parasitic helminths, aε heretofore disclosed, one can use D . immitiε p22U to obtain other parasitic helminth nucleic acid sequenceε that are capable of hybridizing, under stringent conditions, to at least a portion of D . immitiε p22U. Preferred helminths are heretofore disclosed. Particularly preferred p22U-related nucleic acid sequences of the present invention include D . immitis nucleic acid sequence p22U, nucleic acid sequences including D . immitiε p22U, and nucleic acid sequence comprising fragments of D . immitiε p22U (including functional equivalents of each of these nucleic acid sequences) . Knowing the seguence of D . immitis p22U allows one skilled in the art to make copies of the sequence as well as to obtain nucleic acid sequences including D . immitiε p22U and nucleic acid seguences that contain fragments of D . immitis p22U. As such, particularly preferred isolated nucleic acid seguences include SEQ ID NO:3 or a functional equivalent thereof, a nucleic acid sequence containing at least a portion of SEQ ID NO:3 or a functional equivalent thereof, and a fragment of SEQ ID NO:3 or a functional equivalent thereof, assuming the accuracy of SEQ ID NO:3. The present invention also includes an isolated paraεitic helminth protein that iε encoded, at leaεt in part, by a parasitic helminth nucleic acid sequence capable of hybridizing, under stringent conditions, to at least a portion of D. immitis nucleic acid sequence p22U, as well as mimetopes of such a protein. Preferably, the protein or mimetope thereof is also capable of selectively binding to at least one component of anti-parasitic helminth immune serum, and more preferably to anti-L3 and/or L4 larval immune serum. Preferred isolated parasitic helminth proteins or mimetopes thereof are capable of protecting an animal from helminth infection when administered to the animal in an effective manner. Preferred helminths are heretofore disclosed. Particularly preferred isolated proteins include proteinε encoded by D . immitiε nucleic acid seguence p22U, a nucleic acid εequence including D . immitiε p22U, or a nucleic acid sequence comprising a fragment of D . immitiε p22U. As such, particularly preferred isolated proteins are those encoded by SEQ ID NO:3 or a functional equivalent thereof, a nucleic acid sequence containing at least a portion of SEQ ID NO:3 or a functional equivalent thereof, and a fragment of SEQ ID NO:3 or a functional equivalent thereof, as well as proteins that contain at leaεt a portion of SEQ ID NO:4, assuming the accuracy of SEQ ID NO:3 and SEQ ID NO:4. Isolated nucleic acid seguences of the preεent invention can alεo include a nucleic acid that is capable of hybridizing, under stringent conditions, to at least a portion of both D . immitiε nucleic acid sequence p4 and D . immitis nucleic acid sequence p22U. Such a nucleic acid sequence can encode a protein including portions of both P4 and P22U. Alternatively, such a nucleic acid sequence could encode both a P4-related and a P22-related protein. The present invention also includes oligonucleotides that are capable of hybridizing, under stringent conditions, to complementary regionε of other, preferably longer, nucleic acid sequences of the present invention, such as to complementary regions of D. immitiε nucleic acid sequence p4, complementary regions of nucleic acid sequences that include at least a portion of D . immitiε p4, complementary region of nucleic acid sequences that hybridize under stringent conditionε to D . immitis p4, complementary regions of D . immitiε nucleic acid sequence p22U, complementary regions of nucleic acid sequences that include at least a portion of D . immitiε p22U, and complementary regions of nucleic acid sequences that hybridize under stringent conditions to D. immitis p22U. The oligonucleotides can be RNA, DNA, or derivatives of either. The minimal size of such oligonucleotides is the size required to form a stable hybrid between a given oligonucleotide and the complementary seguence on another nucleic acid sequence of the present invention. As such, the size is dependent on nucleic acid composition and percent homology between the oligonucleotide and complementary seguence as well as upon hybridization conditions per se (e.g. , temperature, εalt concentration) . For AT-rich nucleic acid εequences, εuch as thoεe of D . immitiε , oligonucleotides typically are at least about 15 to about 17 bases in length. The size of the oligonucleotide must also be sufficient for the use of the oligonucleotide in accordance with the present invention. Oligonucleotides of the present invention can be used in a variety of applications including, but not limited to, as probes to identify additional nucleic acid sequenceε, aε primers to amplify or extend nucleic acid sequences, or in therapeutic applications to inhibit, for example, expression of nucleic acid sequences into parasitic helminth proteins that are important in the life cycle of the parasite. Such therapeutic applications include the use of such oligonucleotides in, for example, antisense-, triplex formation-, and/or ribozyme-based technologies. For example, antisense oligonucleotides are generally designed as complements to the messenger RNA encoding the desired protein. The complement binds through Watson-Crick base-pairing to the mRNA interfering with translation either by enhancing mRNA degradation by RNAse H, by preventing or inhibiting processing to mature RNA, or by preventing translation. The oligonucleotide may bind either to the translated region or to control sequences in the mRNA. Similarly, as the transcription of DNA involves partial disassembly of the double helix, antisense oligonucleotides may also bind to transcribed or nontranscribed regions of the DNA to inhibit transcription. Absolute homology between the target and. the antisense seguences is preferred but not required for the inhibition. Holt, J.T. et al., Proc Natl Acad Sci (1986) 83:4794. Oligonucleotides may also be designed to form a triplex DNA structure with the intact duplex gene according to certain binding rules. Moffat, A.S., Science (1991) 252:1374-1375. When this triplex structure is formed in the promoter region of a gene, it has been shown to disrupt transcription of that gene. Orson, F.M. et al., Nuc Acids Res (1991) 19:3435-3441. Again, the oligomer designed to form a triplex can be designed to bind the duplex gene in either regulatory or transcribed regions or both. The invention, therefore, also includes methodε to interfere with the production of parasitic helminth proteins by uεe of the antiεenεe or triple helix-forming techniqueε. The relevant oligomers may be administered to a host harboring the parasite in order to effect this control. Isolated nucleic acid sequences of the present invention, such as nucleic acid sequences that hybridize under stringent conditions with either D . immitis p4 or D . immitis p22U, can be obtained in a variety of ways. For example, an isolated nucleic acid sequence of the present invention can be obtained by a method that includes induction of a L3 and/or L4 expression library under conditions that promote production of larval proteins encoded by the library; contacting the library with immune serum collected from an animal that is immune to infection by L3 and/or L4; and selecting a colony or phage plaque that containε a nucleic acid sequence encoding a protein capable of selectively binding to the serum. Conventional culturing and selection methods are taught, for example, in Sambrook et al., ibid . An example of this methodology is also provided in the Examples section. In another embodiment, an isolated nucleic acid sequence is obtained by a method including contacting, under stringent hybridization conditions, at leaεt one oligonucleotide with a paraεitic helminth cDNA library, such that the oligonucleotide includeε nucleic acid sequenceε that encode at leaεt a portion of D . immitiε P4 and/or D . immitiε P22U; and selecting a colony or phage plaque having a nucleic acid seguence that hybridizes under stringent conditions with the oligonucleotide. Alternatively, oligonucleotide primers, including nucleic acid sequences that encode at least portions of D. immitiε P4 and/or D. immitiε P22U, can be used to amplify, by polymerase chain reaction (PCR) amplification, nucleic acid sequenceε that include at least a portion of D . immitiε p4 and/or D. immitiε p22U. An example of these methodologieε is provided in the Examples section. In yet another embodiment, an isolated nucleic acid sequence is obtained by a method including contacting a collection of nucleic acid sequences, such as a parasitic helminth cDNA library, with D. immitiε p4 or a portion thereof, or with D . immitiε p22U or a portion thereof, under stringent hybridization conditions; and identifying a nucleic acid sequence that hybridizes to either D . immitiε p4 or the portion thereof, or with D . immitiε p22U or the portion thereof, under such conditions. Such a technique can be used to clone a nucleic acid sequence using standard hybridization techniques or to amplify a nucleic acid sequence using PCR amplification. Alternatively, serum raised against D . immitiε P4 or D . immitiε P22U could be used to screen cDNA expresεion libraries. The present invention also includeε immunogenε which are isolatable from (i.e., can be isolated from) the L3 and L4 larval stages of nematodes parasitic in mammals which have molecular weights of about 39 kD, about 22 kD, or about 20.5 kd and which can be identified using the method disclosed in Grieve et al., WO/92/13560, ibid . The invention is also directed to corresponding recombinant aspects of these proteins and to immunogenic fragments of the proteins and their recombinant aspects. This embodiment of the invention is illustrated by the identification of 39 kD, 22 kD and 20.5 kD immunogens from D. immitiε , using serum validated by the invention method. The retrieval of genes encoding the immunogens provides suitable probes for retrieval of genes encoding the corresponding proteins in related nematodes capable of parasitism in mammalian hosts. Thus, the invention is directed to the illustrated 39 kD, 22 kD, and 20.5 kD D . immitiε proteins and their related counterpartε which are encoded by DNAε capable of hybridizing under εtandard conditionε to the DNA encoding the reεpective illustrated D. immitiε protein. As such, the present application includes D . immitiε P39, D . immitiε P22L, D . immitiε P20.5, additional parasitic helminth proteins sharing significant homology with D . immitiε P39, D . immitis P22L, or D . immitiε P20.5, nucleic acid seguences encoding any of these proteinε, mimetopes of any of these proteinε, and antibodieε that selectively bind to any of these proteins, as well as uses of these proteins, mimetopes, nucleic acid sequences, and antibodies. The terms "39 kD protein" and "P39" each refer to parasitic helminth proteins of this apparent molecular weight, as determined by Tris-glycine SDS-PAGE, isolatable from the L3 or L4 larval stage of D . immitiε or from related nematodes, or other helminthε, which are parasitic in mammals. The 39 kD protein isolatable from D . immitiε has the amino acid sequences shown hereinbelow. Although the calculated molecular weight of the D. immitis protein is only 39,820, apparent molecular weights may be different, depending on the particular system of measurement used. In particular, P39 migration in Tris- glycine SDS-PAGE indicates a molecular weight of about 39 kD. The term "22/20.5 kD protein" refers to parasitic helminth proteins of these apparent molecular weights isolatable from the L3 or L4 larval stage of D . immitiε or from related nematodes, or other helminths, which are parasitic in mammals. The amino acid sequenceε of the 22/20.5 kD proteins isolatable from D . immitis are disclosed below. As shown, the 20.5 kD protein iε the cleavage product of the 22 kD protein wherein 21 amino acidε of a leader sequence are deleted to yield the smaller protein. Although the calculated molecular weightε of the D . immitiε proteins are only 17.5 kD for the larger and 15.3 kD for the smaller protein, apparent molecular weights may be higher, depending on the particular system of measurement used. The 22 kD and 20.5 kD proteins are also referred to herein as P22L and P20.5, respectively. P22L is the lower, and P22U is the upper, of two bands that migrate at about 22 kD, as separated Tris-glycine SDS PAGE and a molecular weight of about 19 kD as measured by Tris- tricine SDS-PAGE. P20.5 has a molecular weight of about 20.5 kD as measured by Tris-glycine SDS-PAGE and of about 16 kD aε measured by Tris-tricine SDS-PAGE. P39, P22L and P20.5 from D. immitiε are εpecifically immunoreactive with components of immune dog serum which have been validated as protective by the invention method. Similarly, corresponding proteins in other nematode, and other helminth, species parasitic in mammals are specifically immunoreactive with protective components of immune members of the relevant mammalian species, validated by the invention method. The present invention, therefore, provides access to a group of proteins which are contained in the L3 or L4 larval stages of nematodes which are parasitic in mammals and which are useful in preparation of vaccines protective againεt these parasites. The invention provides not only P39, P22L and P20.5, but also the parasitic helminth nucleic acid sequenceε encoding the reεpective proteins. Availability of these nucleic acid sequenceε permits retrieval of homologouε proteins from related nematode and other helminth specieε. The nucleic acid seguences, or portions thereof, can be used as probeε under conditions of standard stringency (i.e., under stringent conditions as defined herein), depending on the library and length of probe, to isolate DNA encoding corresponding proteins in these related species. Further, antibodies immunoreactive with P39 or with P22L and P20.5 of D . immitiε may be used as screening tools to identify nucleic acid εequenceε encoding such proteins in expreεsion librarieε prepared from related species. One embodiment of the present invention is an isolated parasitic helminth nucleic acid sequence that is capable of hybridizing, under stringent conditions, to at least a portion of D. immitiε nucleic acid sequence p39. A protein encoded by such a nucleic acid sequence iε preferably capable of selectively binding to at least one component of anti-parasitic helminth immune serum, and more preferably to anti-L3 and/or L4 larval immune serum. D . immitiε nucleic acid sequence p39, also referred to as D. immitiε p39, is a nucleic acid sequence of about 1100 to about 1200 nucleotides in length that has been isolated from a D . immitiε L3 and/or L4 cDNA expression library using immune serum collected from a dog that was immunized as heretofore disclosed. Genomic sequences including p39 coding sequences also apparently include about 1280 nucleotides comprising one or more introns. Sequencing of D . immitiε p39 cDNA isolates has resulted in the following deduced nucleic acid seguence of the apparent coding region (additional flanking seguences are presented in the Examples) : ATGAT AGATTTGAAG AAGATTGTGG ATGATGAATA TAACATTGAT GTGAAGCCTG ATAAAAATGG CATTGAAGAG AAGAAAGTGA TAGAACTGGA AACGCAGAAT GTGCGGAATG ATGTAGATAA AATTGATAGC GATGATGATG ACTTCCCTGA ATATGAAATT CCTGCAGGAG AATTGATTCT GAAAAAGGAA GAAAATGATG AAGAATATCG CTGTGTAGAA ATCCCATATT ATATTAGGGA TTGTATTGAG TTGCTCAATG AGCAGAATGA TTGTGCCAAA TTTGAGGCTG CATTCAATGC TCTGAAACCA ATGATTAGAC GACGAGCTGT TGGTTATGAA CAATCCGCGG AAGAACTACT CTGCCGACTT ATTGATCTTA GTGATCGCTT CAAAATTGAA CATTTCCAGG AGAAGCGACT ACAGCTTATT GAATCATGTC TAGTGACGAG TCCTTATCTG GGAAATGTAG CTATTGATGT CATGTTTTCG AGAAAATGTT CAATGATGAA TAGATATATC GTTTTAAAGG CTCTATCAGA TGCGGCGTCA GAATATTCAT CTCCAGCCGG AATTGTCGAA AATCCAGCCA TCGAAATTCC AAAAAACGGA GGTGATGTTG AAGGGCATGT CTCTCTCTGC GATGGCGATG GAAAACTGAT CTCCAAGACA AAACTTTTCG TGAGAGCACC AATTACGATG TTAAAGGAAA ACAGATTTAC ACCAATAGCA AATTCCTTCT TCTATCCCTT GACTGCAATC GATCAGCATC GTGAACATCT TGATCTCATT GGGAGAGATT CGGAATTACT GAGTAAGATT CTTTTCTGTA TGGCTCATTT GATCAAATGT TCTGGCACTT CTCCATGTAC GCTTAGAATG TGTAGGTATG TTGACTGA It should be noted that sequencing technology is not entirely error-free and that the above nucleic acid seguence, as such, represents an apparent nucleic acid sequence of D . immitiε p39. The deduced translation of the nucleic acid sequence, namely a deduced D . immitiε P39 amino acid sequence of about 300 amino acids, as follows: MIDLKKIVDD EYNIDVKPDK NGIEEKKVIE LETQNVRNDV DKIDSDDDDF PEYEIPAGEL ILKKEENDEE YRCVEIPYYI RDCIELLNEQ NDCAKFEAAF NALKPMIRRR AVGYEQSAEE LLCRLIDLSD RFKIEHFQEK RLQLIESCLV TSPYLGNVAI DVMFSRKCSM MNRYIVLKAL SDAASEYSSP AGIVENPAIE IPKNGGDVEG HVSLCDGDGK LISKTKLFVR APITMLKENR FTPIANSFFY PLTAIDQHRE HLDLIGRDSE LLSKILFCMA HLIKCSGTSP CTLRMCRYVD. Another embodiment of the present invention is an isolated parasitic helminth nucleic acid sequence that is capable of hybridizing, under stringent conditions, to at least a portion of D . immitiε nucleic acid seguence p22L. A protein encoded by such a nucleic acid sequence is preferably capable of selectively binding to at least one component of anti-parasitic helminth immune serum, and more preferably to anti-L3 and/or L4 larval immune serum. D . immitiε nucleic acid sequence p22L, also referred to as D . immitiε p22L, iε a nucleic acid sequence of about 453 nucleotides in length that has been isolated from a D . immitiε L3 and/or L4 cDNA expression library using immune serum collected from a dog that was immunized as heretofore disclosed. Sequencing of a P. immitiε p22L cDNA has resulted in the following nucleic acid sequence of the apparent coding region: ATGAACAAAC TTTTCATAGT TCTTGGCTTA GCGCTTCTTT TTGTTGCATT ACCTTCCGCA TCAGAATCAC AAGAAGAGAC TGTATCTTTT GAAGAAAGCG ACGAAGATTA TGAAGACGAT AGTGAAGATC AAACAAAAGA AGAGGAACAT TCAAAAGAGG AAGATCGTTC AGAAGAACAC GACGATCATT CAGCTGAAGA CGATAAATTT GTAACTAAAG GAAAATTTGT TGAAAGTGAC GGCAAGATGA AGCATTGCAA AACCCATGAA GCTTGCTATG ATCAACGTGA ACCACAATCG TGGTGCATAT TAAAACCGCA TCAGTCATGG ACACAAAGAG GTTGTTTCTG CGAATCAAAA AAACATGCAT GCGTTATCGA ACGAAAAAGC GGCGACAAAT TGGAATATTC GTATTGCTCA CCCCGAAAAA ACTGGCAGTG TTCATACGAT TAA. It should be noted that seguencing technology is not entirely error-free and that the above nucleic acid sequence, as such, represents an apparent nucleic acid sequence of D . immitiε p22L. The deduced translation of the nucleic acid sequence, namely a deduced D . immitiε P22L amino acid sequence of about 150 amino acids, as follows: MNKLFIVLGL ALLFVALPSA SESQEETVSF EESDEDYEDD SEDQTKEEEH SKEEDRSEEH DDHSAEDDKF VTKGKFVESD GKMKHCKTHE ACYDQREPQS WCILKPHQSW TQRGCFCESK KHACVIERKS GDKLEYSYCS PRKNWQCSYD. The C-terminal half of P22L is further characterized by sharing at least some amino acid seguence homology with a variety of phospholipase A 2 (PLA2) amino acid sequenceε, the similarities being particularly well conserved with respect to cysteines and the amino acids comprising the active site. A BLAST search of the NCBI non-redundant data library (SWISS-PROT ver. 23.0, PIR ver. 34.0, GenPept CDS translations from GenBank release 73.1) using amino acids 80-104 (DGKMK HCKTH EACYD QREPQ SWCIL) of the deduced P22L amino acid sequence yielded 40 records, 39 of which were PLA2 sequences. Twenty-five of the 29 SWISS-PLOT match sequences represent PLA2 venoms from a variety of snakeε while the other 4 sequences were mammalian pancreatic PLA2 sequences. No non-mammal, non-arthropod eukaryotic entries were found. PLA2 catalyzes the hydrolysis of the 2-acyl ester group of sn-3-glycerophospholipids. Potential roleε of a PLA2 activity in parasites include lipid metabolism; membrane synthesis, remodeling and/or separation (e.g., aε part of the molting process) ; and/or in migration (e.g. , PLA2 could aid in disrupting host cell membranes during the tissue migration that occurs during L4) . Aε such, the finding of homologous seguences between the C-terminal portion of P22L (and, inherently, P20.5) and PLA2 suggest the targeting of such sequences in the development of anti- parasite therapeutics that block PLA2 activity, thereby protecting animals from parasite helminth infections. Yet another embodiment of the present invention is an isolated parasitic helminth nucleic acid sequence that is capable of hybridizing, under stringent conditions, to at least a portion of D . immitiε nucleic acid sequence p20.5. A protein encoded by such a nucleic acid sequence is preferably capable of selectively binding to at least one component of anti-parasitic helminth immune serum, and more preferably to anti-L3 and/or L4 larval immune serum. D . immitiε nucleic acid sequence p20.5, also referred to aε D . immitiε p20.5, is a nucleic acid sequence of about 390 nucleotideε in length that haε been isolated from a D . immitis L3 and/or L4 cDNA expreεsion library using immune serum collected from a dog that was immunized as heretofore disclosed. Seguencing of D . immitiε p20.5 has resulted in the following nucleic acid sequence of the apparent coding region: GAATCAC AAGAAGAGAC TGTATCTTTT GAAGAAAGCG ACGAAGATTA TGAAGACGAT AGTGAAGATC AAACAAAAGA AGAGGAACAT TCAAAAGAGG AAGATCGTTC AGAAGAACAC GACGATCATT CAGCTGAAGA CGATAAATTT GTAACTAAAG GAAAATTTGT TGAAAGTGAC GGCAAGATGA AGCATTGCAA AACCCATGAA GCTTGCTATG ATCAACGTGA ACCACAATCG TGGTGCATAT TAAAACCGCA TCAGTCATGG ACACAAAGAG GTTGTTTCTG CGAATCAAAA AAACATGCAT GCGTTATCGA ACGAAAAAGC GGCGACAAAT TGGAATATTC GTATTGCTCA CCCCGAAAAA ACTGGCAGTG TTCATACGAT TAA. It should be noted that sequencing technology is not entirely error-free and that the above nucleic acid sequence, as such, represents an apparent nucleic acid sequence of D . immitiε p20.5. The deduced translation of the nucleic acid sequence, namely a deduced D . immitiε P20.5 amino acid εequence of about 129 amino acidε, aε follows: ESQEETVSF EESDEDYEDD SEDQTKEEEH SKEEDRSEEH DDHSAEDDKF VTKGKFVESD GKMKHCKTHE ACYDQREPQS WCILKPHQSW TQRGCFCESK KHACVIERKS GDKLEYSYCS PRKNWQCSYD. As disclosed for nucleic acid sequences p4 and p22U, nucleic acid sequences of the present invention encoding P39 (i.e., p39) , P22L (i.e., p22L) and L20.5 (i.e., p20.5) include allelic variants and fragments thereof, including oligonucleotides having a variety of uses. Methods to isolate and use nucleic acid sequences p39, p22L and p20.5 as well aε the proteins encoded by them are εimilar to those used in the isolation and use of p4 and p22U. Selected examples are diεcloεed in the examples section. The present invention also includes recombinant vectors, which include a parasitic helminth nucleic acid sequence of the present invention inserted into any vector capable of delivering the nucleic acid into a host cell. The vector contains heterologous nucleic acid sequenceε, that is nucleic acid sequences that are not naturally found adjacent to parasitic helminth nucleic acid sequences of the present invention and that preferably are derived from a species other than the species from which the parasitic helminth nucleic acid εequenceε are derived. The vector can be either RNA or DNA, either prokaryotic or eukaryotic, and typically is a virus or a plasmid. Recombinant vectors can be used in the cloning, seguencing, and/or otherwise manipulating of nucleic acid sequenceε of the present invention. One type of recombinant vector, herein referred to as a recombinant molecule and described in more detail below, can be used in the expression of nucleic acid sequences of the present invention. Preferred recombinant vectors are capable of replicating in the transformed cell. Preferred nucleic acid seguences to include in recombinant vectors of the present invention include parasitic helminth nucleic acid sequences capable of hybridizing, under stringent conditions, to at leaεt a portion of D. immitiε nucleic acid sequence p4, to at least a portion of D. immitiε nucleic acid sequence p22U, to at least a portion of D . immitiε nucleic acid sequence p39, to at least a portion of D . immitiε nucleic acid sequence p22L, or to least a portion of D . immitiε nucleic acid sequence p20.5. Particularly preferred nucleic acid sequences to include in recombinant vectors include D . immitiε nucleic acid sequence p4, nucleic acid sequenceε including D . immitiε p4, nucleic acid sequence comprising fragments of D . immitis p4, D. immitis nucleic acid seguence p22U, nucleic acid sequences including D . immitis p22U, and nucleic acid sequence comprising fragments of D . immitiε p22U. Additional particularly preferred nucleic acid sequences to included in recombinant vectors include D . immitiε nucleic acid sequence p39, nucleic acid sequences including D . immitiε p39, nucleic acid sequence comprising fragments of D . immitis p39, D. immitiε nucleic acid sequence p22L, nucleic acid sequences including D . immitiε p22L, nucleic acid sequence comprising fragments of D . immitis p22L, D . immitiε nucleic acid sequence p20.5, nucleic acid sequences including D. immitiε p20.5, and nucleic acid seguence comprising fragments of D. immitiε p20.5. Isolated proteins of the present invention can be produced in a variety of ways, including production and recovery of natural proteins, production and recovery of recombinant proteins, and chemical synthesiε. In one embodiment, an isolated protein of the present invention is produced by culturing a cell capable of expressing the protein under conditions effective to produce said protein, and recovering the protein. A preferred cell to culture is a recombinant cell that is capable of expressing the protein, the recombinant cell being produced by transforming a host cell with one or more nucleic acid seguences of the present invention. Transformation of a nucleic acid sequence into a host cell can be accomplished by any method by which a nucleic acid sequence can be inserted into a cell. Transformation techniques include, but are not limited to, transfection, electroporation, microinjection, lipofection, adsorption, and protoplast fusion. A recombinant cell may remain unicellular or may grow into a tisεue, organ or a multicellular organiεm. Tranεformed nucleic acid sequenceε of the preεent invention can remain extrachromosomal or can integrate into one or more sites within a chromosome of a host cell in such a manner that their ability to be expressed is retained. Preferred nucleic acid seguences with which to transform cells include parasitic helminth nucleic acid sequences capable of hybridizing, under stringent conditions, to at least a portion of D . immitiε nucleic acid sequence p4, to at least a portion of D . immitiε nucleic acid sequence p22U, to at least a portion of D . immitiε nucleic acid sequence p39, to at least a portion of D. immitiε nucleic acid sequence p22L, or to least a portion of D . immitiε nucleic acid sequence p20.5. Particularly preferred nucleic acid sequences with which to transform cells include D . immitiε nucleic acid sequence p4, nucleic acid sequences including D . immitiε p4, nucleic acid sequence comprising fragments of D . immitiε p4, D . immitis nucleic acid sequence p22U, nucleic acid sequenceε including D . immitiε p22U, and nucleic acid εequence compriεing fragments of D . immitiε p22U. Additional particularly preferred nucleic acid sequences with which to transform cells include D . immitiε nucleic acid sequence p39, nucleic acid sequences including D . immitiε p39, nucleic acid sequence comprising fragments of D . immitiε p39, D. immitiε nucleic acid sequence p22L, nucleic acid sequenceε including D . immitiε p22L, nucleic acid εeguence compriεing fragmentε of D . immitiε p22L, D . immitiε nucleic acid sequence p20.5, nucleic acid sequences including D . immitiε p20.5, and nucleic acid sequence comprising fragments of D . immitiε p20.5. Suitable host cells to transform include any cell that can be transformed. Host cells can be either untransformed cells or cells that are already transformed with at leaεt one nucleic acid sequence. Host cells of the preεent invention either can be endogenously (i.e., naturally) capable of producing isolated proteins of the present invention or can be capable of producing such proteins after being transformed with at least one nucleic acid sequence of the present invention. Host cells of the present invention can be any cell capable of producing an isolated protein of the present invention, including bacterial, yeast, other fungal, insect, animal, and plant cells. Preferred host cells include bacterial, mycobacterial, yeast, insect and mammalian cells, and more preferred host cells include Salmonella , Escherichia , Bacillus , Saccharomyceε, Spodoptera , Mycobacteria , Trichopluεia , BHK (baby hamster kidney) cells, MDCK cells (normal dog kidney cell line for canine herpesvirus cultivation) , CRFK cells (normal cat kidney cell line for feline herpesviruε cultivation) and COS cellε. Particularly preferred host cells are Eεcherichia coli , including E . coli K-12 derivativeε; Salmonella typhi ; Salmonella typhimurium , including attenuated εtrainε such as UK-1 v 3987 and SR-11 v 4072; Spodoptera frugiperda Trichopluεia ni ; MDCK cells; and CRFK cells. Additional appropriate mammalian cell hosts include other kidney cell lines (e.g., CV-1 monkey kidney cell lines) , other fibroblaεt cell lineε (e.g. , human, murine or chicken embryo fibroblaεt cell lines) , Chinese hamster ovary (CHO) cells, HeLa cells, mouse NIH/3T3 and/or LMTK 31 cells. Alternatively, the proteins may be expressed as heterologous protein in myeloma cell lines employing immunoglobulin promoters. A recombinant cell is preferably produced by transforming a host cell with one or more recombinant molecules, each comprising one or more nucleic acid seguences of the present invention operatively linked to an expression vector containing one or more transcription control sequences. A cell can be transformed with one or more recombinant molecules. The phrase operatively linked, or operably linked, refers to insertion of a nucleic acid sequence into an expression vector in a manner such that the sequence is able to be expresεed when transformed into a host cell. As used herein, an expresεion vector is a DNA or RNA vector that is capable of tranεforming a hoεt cell, of replicating within the host cell, and of effecting expression of a specified nucleic acid sequence. Expression vectors can be either prokaryotic or eukaryotic, and are typically viruses or plasmids. Expression vectors of the present invention include any vectors that function (i.e.,direct gene expression) in recombinant cells of the present invention, including in bacterial, yeast, other fungal, insect, animal, and plant cells. Preferred expression vectors of the present invention can direct gene expression in bacterial, yeast, insect and mammalian cells and more preferably in the cell types heretofore disclosed. Expression vectors of the present invention may alεo contain secretory signals to enable an expressed parasitic helminth protein to be secreted from its host cell or may contain fusion sequenceε which lead to the expreεsion of inserted nucleic acid sequences of the present invention as fusion proteins. Eukaryotic recombinant molecules may include intervening and/or untranslated sequences surrounding and/or within parasitic helminth nucleic acid sequences. Nucleic acid sequences of the present invention can be operatively linked to expresεion vectors containing regulatory seguences such as promoters, operators, repressors, enhancers, termination sequences, origins of replication, and other regulatory sequences that are compatible with the host cell and that control the expresεion of the nucleic acid sequences. In particular, recombinant molecules of the present invention include transcription control sequences. Transcription control sequences are sequences which control the initiation, elongation, and termination of transcription. Particularly important transcription control seguences are those which control transcription initiation, such as promoter, enhancer, operator and represεor εequenceε. Suitable tranεcription control εequenceε include any tranεcription control sequence that can function in at least one of the recombinant cells of the present invention. A variety of such transcription control εequenceε are known to those skilled in the art. Preferred tranεcription control sequences include those which function in bacterial, yeast, helminths, helminth cells, insect and mammalian cells, such as, but not limited to, tac , lac , trp, trc, oxy-pro, bacteriophage lambda (such as lambda p L and lambda p R ) , bacteriophage T7, T72ac, bacteriophage T3, bacteriophage SP6, bacteriophage SP01, metallothionein, alpha mating factor, Pichia alcohol oxidase, alphavirus subgenomic promoters (such as Sindbis virus subgenomic promoters) , baculovirus, Heliothis zea insect virus, vaccinia virus, adenovirus, simian virus 40, retrovirus actin, Rouε sarcoma virus, heat shock, phosphate and nitrate transcription control sequences as well as other sequenceε capable of controlling gene expresεion in prokaryotic or eukaryotic cells. Transcription control εequences of the present invention can alεo include naturally occurring transcription control sequences previously associated with a nucleic acid sequence prior to isolation. A recombinant molecule of the present invention can be any nucleic acid sequence heretofore described operatively linked to any transcription control sequence capable of effectively regulating expreεεion of the nucleic acid sequence in the cell to be transformed. Preferred recombinant molecules include parasitic helminth nucleic acid sequences capable of hybridizing, under stringent conditions, to at least a portion of D . immitiε nucleic acid sequence p4, to at least a portion of D . immitiε nucleic acid sequence p22U, to at least a portion of D . immitiε nucleic acid εequence p39, to at leaεt a portion of D. immitis nucleic acid sequence p22L, or to leaεt a portion of D . immitis nucleic acid sequence p20.5. Particularly preferred recombinant molecules contain D . immitiε nucleic acid sequence p4, nucleic acid sequences including D . immitiε p4, nucleic acid sequence comprising fragments of D. immitiε p4, D . immitiε nucleic acid sequence p22U, nucleic acid sequences including D . immitis p22U, and nucleic acid sequence comprising fragments of D . immitis p22U. Additional particularly preferred recombinant molecules contain D . immitiε nucleic acid sequence p39, nucleic acid sequences including D . immitiε p39, nucleic acid seguence comprising fragments of D . immitis p39, D . immitiε nucleic acid sequence p22L, nucleic acid seguences including D . immitiε p22L, nucleic acid seguence comprising fragments of D . immitiε p22L, D . immitiε nucleic acid seguence p20.5, nucleic acid sequenceε including D . immitiε p20.5, or nucleic acid εeguence comprising fragments of D . immitiε p20.5. Even more preferred recombinant molecules include p3gal-p4, pHis-p4 , pET19b-p4 635 , p/3gal-p22U, pHiε-p22U, and pHiε-p22U 608 . Additional even more preferred recombinant molecules include pHis-p39 900 , p76-80.B3, pl05-72.5C, pl05-42.1A, pETl9b-PLA2 47 , p76-79-A6, p76-79.C2 and p88-36.1B. The Examples section includes deεcriptionε of the derivationε of such recombinant molecules. Recombinant cells of the present invention include any cells transformed with any nucleic acid sequences of the present invention. Preferred recombinant cells are transformed with recombinant molecules containing at leaεt one of the following: a parasitic helminth nucleic acid seguence capable of hybridizing, under stringent conditions, to at least a portion of D . immitiε nucleic acid sequence p4, to at least a portion of D. immitiε nucleic acid sequence p22U, to at least a portion of D . immitiε nucleic acid sequence p39, to at least a portion of D . immitiε nucleic acid sequence p22L, or to least a portion of D . immitiε nucleic acid sequence p20.5. More preferred recombinant cells are transformed with recombinant moleculeε including D . immitiε nucleic acid seguence p4, nucleic acid seguences including D . immitiε p4, nucleic acid sequence comprising fragments of D . immitiε p4 , D . immitiε nucleic acid sequence p22U, nucleic acid sequences including D. immitiε p22U, and/or nucleic acid sequence comprising fragments of D . immitiε p22U. Additional particularly preferred recombinant cells are transformed with recombinant molecules including D . immitiε nucleic acid sequence p39, nucleic acid sequences including D. immitiε p39, nucleic acid sequence comprising fragments of D . immitiε p39, D . immitiε nucleic acid sequence p22L, nucleic acid sequences including D . immitiε p22L, nucleic acid sequence comprising fragments of D . immitiε p22L, D . immitiε nucleic acid sequence p20.5, nucleic acid sequences including D. immitiε p20.5, or nucleic acid sequence comprising fragments of D A immitiε p20.5. Such recombinant cells can also be co-transformed with recombinant molecules including nucleic acid sequences encoding one or more other helminth parasitic proteins including those heretofore disclosed and/or D. immitiε Di22 and D . immitis proteases expressed in L3 and/or L4 larvae, as well as other helminth proteins sharing significant homology with such proteins. The nucleic acid sequence encoding Di22 is disclosed in GenBank data base accession number M82811. The protease is disclosed in Grieve et al., PCT International Publication No. WO 93/10225, published May 27, 1993. Particularly preferred recombinant cells include E. coli :p0gal-p4, E. coli:pHiε-p4, E. coli:pET19b-p4 635 , E. coli:p)8gal-p22U, E . coli:pHis-p22U and E . coli:pHiε-p22U 608 . Additional particularly preferred recombinant cells include E . coli:pHiε-p39 900 , S . frugiperda :pl05-72.5C, BHK:pl05-42.IA, E . coli:pET19b-PLA2-,i 7 , S . rrugiperda:p76-79-A6p76-79-A6 and BHK:p88-36.1B. It may be appreciated by one skilled in the art that use of recombinant DNA technologies can improve expresεion of transformed nucleic acid seguenceε by manipulating, for example, the number of copies of the nucleic acid sequences within a host cell, the efficiency with which those nucleic acid sequences are transcribed, the efficiency with which the resultant transcriptε are translated, and the efficiency of post-translational modifications. Recombinant techniqueε uεeful for increasing the expression of nucleic acid seguences of the present invention include, but are not limited to, operatively linking nucleic acid sequences to high-copy number plasmidε, integration of the nucleic acid sequences into one or more host cell chromosomes, addition of vector stability sequences to plasmids, substitutions or modifications of transcription control signals (e.g., promoters, operators, enhancers), substitutions or modifications of translational control signals (e.g., riboso e binding sites, Shine-Dalgarno sequences) , modification of nucleic acid sequences of the present invention to correspond to the codon usage of the host cell, deletion of sequences that destabilize transcripts, and use of control signals that temporally separate recombinant cell growth from recombinant enzyme production during fermentation. The activity of an expressed recombinant protein of the present invention may be improved by fragmenting, modifying, or derivatizing nucleic acid seguences encoding such a protein. In accordance with the preεent invention, recombinant cells can be used to produce at least one parasitic helminth protein of the present by culturing such cells under conditions effective to produce such a protein, and recovering the protein. Effective conditions to produce a protein include, but are not limited to, appropriate media, bioreactor, temperature, pH and oxygen conditions that permit protein production. An appropriate medium refers to any medium in which a cell of the present invention, when cultured, is capable of producing parasitic helminth proteins. An effective medium is typically an aqueous medium comprising assimilable carbohydrate, nitrogen and phosphate sources, as well as appropriate εalts, minerals, metals and other nutrients, such as vitamins. The medium may comprise complex nutrients or may be a defined minimal medium. Cells of the present invention can be cultured in conventional fermentation bioreactors, which include, but are not limited to, batch, fed-batch, cell recycle, and continuous fermentors. Culturing can alεo be conducted in shake flasks, test tubes, microtiter dishes, and petri plates. Culturing is carried out at a temperature, pH and oxygen content appropriate for the recombinant cell. Such culturing conditions are well within the expertise of one of ordinary skill in the art. Examples of suitable conditions are included in the Examples section. Depending on the vector and host system used for production, resultant proteinε may either remain within the recombinant cell; be secreted into the fermentation medium; be secreted into a space between two cellular membranes, such as the periplasmic space in E . coli ; or be retained on the outer surface of a cell or viral membrane. The phrase "recovering the protein" referε simply to collecting the whole fermentation medium containing the protein and need not imply additional steps of separation or purification. Parasitic helminth proteins of the present invention can be purified using a variety of standard protein purification techniques, such as, but not limited to, affinity chromatography, ion exchange chromatography, filtration, electrophoresis, hydrophobic interaction chromatography, gel filtration chromatography, reverse phase chromatography, chromatofocusing and differential solubilization. Isolated parasitic helminth proteinε are preferably retrieved in "substantially pure" form. As used herein, "substantially pure" refers to a purity that allows for the effective use of the protein as a therapeutic composition or diagnostic. A vaccine for animals, for example, should exhibit no subεtantial toxicity and should be capable of stimulating the production of antibodies in a vaccinated animal. One embodiment of the present invention is the expression of a parasitic helminth protein as a fusion protein which includes the parasitic helminth protein attached to a fusion segment. Such a fusion segment often aids in protein purification, εuch as permitting one to purify the resultant fusion protein using affinity chromatography. Fusion proteins can be produced by culturing a recombinant cell transformed with a fusion nucleic acid sequence that encodes a protein including the fusion segment attached to either the carboxyl and/or amino terminal end of the parasitic helminth protein. Preferred fusion segments include, but are not limited to, glutathione-S-transferase, β-galactosidase, a poly- histidine segment capable of binding to a divalent metal ion, maltose binding protein and immunoglobulin binding domains (e.g., protein A or portions thereof) with a poly- histidine segment being more preferred. Examples of fusion proteinε of the present invention include P3GAL-P4, PHIS- P4, PHIS-P4 635 , P3GAL-P22U, PHIS-P22U, PHIS-P22U 608 , PHIS- P39 90 o, and PHIS-PLA2-, 17 (alεo denoted PHIS-P22L- >17 ) . The present invention also includes antibodieε capable of selectively binding to a parasitic helminth protein or mimetope thereof, the protein or mimetope thereof being capable of selectively binding to at leaεt one component of anti-parasitic helminth immune serum. Such antibodies can be either polyclonal or monoclonal antibodies. Antibodies of the present invention include functional equivalents such as antibody fragments and genetically-engineered antibodieε, including single chain antibodies, that are capable of selectively binding to at least one of the epitopes of the protein or mimetope used to obtain the antibodies. Preferred antibodies are raised in response to proteins, or mimetopes thereof, that are encoded, at least in part, by a nucleic acid sequence capable of hybridizing, under stringent conditions, to at least a portion of D . immitis nucleic acid sequence p4, to at least a portion of D . immitiε nucleic acid sequence p22U, to at least a portion of D . immitiε nucleic acid sequence p39, to at least a portion of D . immitiε nucleic acid sequence p22L, or to at least a portion of D . immitiε nucleic acid sequence p20.5. A preferred method to produce antibodies of the present invention includes administering to an animal an effective amount of an isolated protein or mimetope thereof to produce the antibody, wherein the protein is capable of selectively binding to at least one component of εerum from an animal that iε immune to infection by the helminth, the serum being capable of inhibiting helminth development; and recovering the antibodies. Preferably the protein is encoded, at least in part, by a parasitic helminth nucleic acid sequence capable of hybridizing, under stringent conditions, to at least a portion of D . immitis nucleic acid sequence p4, to at least a portion of D . immitiε nucleic acid sequence p22U, to at least a portion of D . immitis nucleic acid sequence p39, to at least a portion of D . immitis nucleic acid sequence p22L, or to at least a portion of D. immitiε nucleic acid sequence p20.5. Antibodies raised against defined proteins or mimetopes can be advantageous because such antibodies are not substantially contaminated with antibodies against other substances that might otherwise cauεe interference in a diagnostic assay or side effects if used in a therapeutic composition. Antibodies of the present invention have a variety of potential uses that are within the scope of the present invention. For example, such antibodies can be used (a) as vaccines to passively immunize an animal in order to protect the animal from parasitic helminth infections, (b) as reagents in assays to detect parasitic helminth infection, and/or (c) as tools to recover desired paraεitic helminth proteins from a mixture of proteins and other contaminants. Furthermore, antibodies of the preεent invention can be used to target cytotoxic agents to parasitic helminths in order to directly kill helminths expressing proteins selectively bound by the antibodieε. Targeting can be accomplished by conjugating (i.e., stably joining) such antibodies to the cytotoxic agents. Suitable cytotoxic agents include, but are not limited to: double-chain toxins (i.e., toxins having A and B chains), such as diphtheria toxin, ricin toxin, Pεeudomonas exotoxin, modeccin toxin, abrin toxin, and shiga toxin; single-chain toxins, such as pokeweed antiviral protein, α-amanitin, and ribosome inhibiting proteins; and chemical toxins, such aε melphalan, methotrexate, nitrogen mustard, doxorubicin and daunomycin. Preferred double-chain toxins are modified to include the toxic domain and translocation domain of the toxin but lack the toxin's intrinsic cell binding domain. One embodiment of the present invention is a therapeutic composition capable of protecting an animal from parasitic helminth infection when administered to the animal in an effective manner. Such a composition includes at least one of the following protective compounds: (a) an isolated parasitic helminth protein, or mimetope thereof, capable of selectively binding to at leaεt one component of an anti-parasitic helminth immune serum such that the protein is preferably encoded, at least in part, by a nucleic acid seguence capable of hybridizing, under stringent conditions, to at least a portion of D . immitis nucleic acid seguence p4; (b) an isolated parasitic helminth protein, or mimetope thereof, capable of selectively binding to at least one component of an anti- parasitic helminth immune serum such that the protein is preferably encoded, at least in part, by a nucleic acid sequence capable of hybridizing, under stringent conditions, to at least a portion of D . immitiε nucleic acid sequence p22U; (c) an antibody capable of selectively binding to a paraεitic helminth protein or mimetope thereof, that iε capable of selectively binding to at least one component of an anti-parasitic helminth immune serum such that the protein is preferably encoded, at least in part, by a nucleic acid sequence capable of hybridizing, under stringent conditions, to at least a portion of D . immitis nucleic acid sequence p4; (d) an antibody capable of selectively binding to a parasitic helminth protein or mimetope thereof, that is capable of selectively binding to at least one component of an anti-parasitic helminth immune serum such that the protein is preferably encoded, at least in part, by a nucleic acid sequence capable of hybridizing, under stringent conditions, to at least a portion of D . immitis nucleic acid seguence p22U; (e) an isolated parasitic helminth nucleic acid sequence capable of hybridizing, under stringent conditions, to at leaεt a portion of D . immitiε nucleic acid sequence p4; and/or (f) an isolated parasitic helminth nucleic acid sequence capable of hybridizing, under stringent conditions, to at least a portion of D . immitiε nucleic acid sequence p22U. Also included in the present invention are therapeutic compoεitionε including at least one of the following: isolated parasitic helminth proteins P39, P22L, and/or P20.5; antibodies that bind selectively to at least one of those proteins; and/or nucleic acid sequences capable of hybridizing, under εtringent conditionε, to at leaεt a portion of D . immitiε nucleic acid sequence p39, p22L, and/or p20.5. Administration of a therapeutic composition containing multiple protective compounds targeting multiple parasitic helminths to an animal can protect the animal from infection by those helminths. Similarly, administration of a therapeutic composition targeting different aspects of a given parasitic helminth may provide additional protection to the animal. For example, a therapeutic composition of the present invention including P4 and/or P22u can also include at least one of the following additional compounds: D . immitiε P39, D . immitiε P22L, D . immitiε P20.5, D . immitiε Di22, and D. immitiε proteaseε expreεεed in L3 and/or L4 larvae, aε well aε other helminth proteinε sharing significant homology with D . immitiε P39, D . immitiε P22L, D . immitiε P20.5, D . immitiε Di22, and D . immitiε proteases expressed in L3 and/or L4 larvae, as well as mimetopes of such proteins, antibodies that selectively bind to such proteins or mimetopes thereof, and nucleic acid sequences encoding such proteins. As used herein, a protective compound refers to a compound that when administered to an animal in an effective manner iε able to treat, ameliorate, and/or prevent infection by a paraεitic helminth. Preferred helminths are heretofore disclosed. Therapeutic compositionε of the preεent invention can be administered to any animal, preferably to mammals, and more preferably to dogs, cats, humanε, ferrets, horses, cattle, sheep and other pets and/or economic food animals. Preferred animals to protect include dogs, cats, humans and ferrets, with dogε and cats being particularly preferred. Therapeutic compositions of the present invention can be formulated in an excipient that the animal to be treated can tolerate. Examples of such excipients include water, saline, Ringer's solution, dextrose solution, Hank's solution, and other aqueous physiologically balanced salt solutions. Nonaqueous vehicles, such as fixed oils, sesame oil, ethyl oleate, or triglycerides may also be used. Other useful formulations include suspensions containing viscosity enhancing agents, εuch as sodium carboxymethylcellulose, εorbitol, or dextran. Excipientε can also contain minor amounts of additives, such as substances that enhance isotonicity and chemical stability. Examples of buffers include phosphate buffer, bicarbonate buffer and Triε buffer, while exampleε of preservatives include thimerosal, m or o-cresol, formalin and benzyl alcohol. Standard formulations will either be liquid injectables or solids which can be taken up in a suitable liquid as a suspension or solution for injection. Thus, in a non-liquid formulation, the excipient may comprise dextrose, human serum albumin, preservatives, etc., to which sterile water or saline could be added prior to administration. In one embodiment of the present invention, the therapeutic compoεition can also include an immunopotentiator, such as an adjuvant or a carrier. Adjuvants are typically substances that generally enhance the immune response of an animal to a specific antigen. Suitable adjuvants include, but are not limited to, Freund's adjuvant; other bacterial cell wall components; aluminum-based salts; calcium-based salts; silica; polynucleotides; toxoids; serum proteins; viral coat proteins; other bacterial-derived preparations; gamma interferon; block copolymer adjuvantε, such as Hunter's Titer ax adjuvant (Vaxcel™, Inc. Norcross, GA) ; Ribi adjuvants (available from Ribi ImmunoChem Research, Inc. , Hamilton, MT) ; and saponins and their derivativeε, such as Quil A (available from Superfos Biosector A/S, Denmark). Carrierε are typically compounds that increase the half- life of a therapeutic composition in the treated animal. Suitable carriers include, but are not limited to, polymeric controlled release formulations, biodegradable implants, liposomes, bacteria, other viruses, oils, esters, and glycols. In order to protect an animal from parasitic helminth infection, a therapeutic composition of the present invention is administered to the animal in an effective manner such that the composition is capable of protecting that animal from infection. For example, an isolated protein or mimetope thereof, when adminiεtered to an animal in an effective manner, iε able to elicit (i.e., stimulate) an immune response, preferably including both a humoral and cellular response, that is sufficient to protect the animal from infection. Similarly, an antibody of the present invention, when administered to an animal in an effective manner, is administered in an amount so as to be present in the animal at a titer that is sufficient to protect the animal from infection, at least temporarily. Nucleic acid sequences of the present invention, preferably oligonucleotides, can also be administered in an effective manner, thereby reducing expression of parasitic helminth proteins in order to interfere with parasite development. Therapeutic compositions of the present invention can be administered to animals prior to parasite infection in order to prevent infection and/or can be administered to animals after parasite infection in order to treat disease caused by the parasite. For example, proteins, mimetopes thereof, and antibodieε thereof can be used as immunotherapeutic agents. Acceptable protocols to administer therapeutic compositions in an effective manner include individual dose size, number of doses, frequency of dose administration, and mode of administration. Determination of such protocols can be accomplished by those skilled in the art. A suitable single dose iε a dose that is capable of protecting an animal from parasitic helminth infection when administered one or more times over a suitable time period. For example, a preferred single dose of a protein, mimetope or antibody therapeutic composition is from about 1 microgram (μg) to about 10 milligrams (mg) of the therapeutic composition for an animal about the size of a dog. Booster vaccinations can be administered from about 2 weeks to several years after the original administration. Preferably booster vaccinations are administered when the immune response of the animal becomes insufficient to protect the animal from parasitic helminth infection. A preferred administration schedule is one in which from about 10 μg to about 1 mg of the vaccine per kg body weight of the animal is administered from about one to about two times over a time period of from about 2 weeks to about 12 months. Modes of administration can include, but are not limited to, subcutaneous, intradermal, intravenous, nasal, oral, transdermal and intramuscular routes. According to one embodiment, nucleic acid sequences of the present invention can also be administered to an animal in a fashion to enable expression of the nucleic acid sequence into a protective protein in the animal to be protected from parasitic helminth infection. Nucleic acid sequences can be delivered in a variety of methodε including, but not limited to, direct injection (e.g., as "naked" DNA or RNA molecules, such as is taught, for example in Wolff et al., 1990, Science 247, 1465-1468), packaged as a recombinant virus particle vaccine, and packaged as a recombinant cell vaccine. A recombinant virus particle vaccine of the present invention includes a recombinant molecule of the present invention that is packaged in a viral coat and that can be expressed in an animal after administration. Preferably, the recombinant molecule is packaging-deficient. A number of recombinant virus particles can be uεed, including, but not limited to, thoεe based on alphaviruses, pox viruεeε, adenoviruses, herpes viruses, and retroviruses. Preferred recombinant particle viruses are those based on alphaviruses, with those based on Sindbiε virus, Semliki virus, and Ross River virus being more preferred. Methods to produce and use recombinant virus particle vaccines are disclosed in U.S. Patent Application Serial No. 08/015/414, filed February 8, 1993, entitled "Recombinant Virus Particle Vaccines". When administered to an animal, the recombinant virus particle vaccine infects cells within the immunized animal and directs the production of a parasitic helminth protein or RNA that is capable of protecting the animal from infection by the helminth. For example, when the helminth protein is a D . immitiε protein, the recombinant virus particle vaccine is administered according to a protocol that results in the animal producing a sufficient immune response to protect itself from heartworm. A preferred single dose of a recombinant virus particle vaccine of the present invention is from about 1 x 10 4 to about 1 x 10 5 virus plaque forming units (pfu) per kilogram body weight of the animal. Adminiεtration protocolε are similar to those described herein for protein-based vaccines. A recombinant cell vaccine of the present invention includes recombinant cells of the present invention that express at least one parasitic helminth protein. Preferred recombinant cells include Salmonella , Eεcherichia coli , and Mycobacterium recombinant cells, with Salmonella recombinant cells being more preferred. Such recombinant cells can be administered in a variety of ways but have the advantage that they can be adminiεtered orally, preferably at doses ranging from about 10 8 to about 10 12 bacteria per kilogram body weight. Administration protocols are similar to those described herein for protein-based vaccines. In common with most other enteric pathogens, Salmonella strains normally enter the host orally. Once in the intestine, they interact with the mucosal surface, normally to establish an invasive infection. Most Salmonella infectionε are controlled at the epithelial surface, causing the typical Salmonella-induced gastroenteritis. Some strains of Salmonella , including S . typhi and some S . typhimurium isolates, have evolved the ability to penetrate deeper into the host, causing a disseminated systemic infection. It appears such strains have the capacity to resist the killing actions of macrophages and other immune cells. S . typhi can exist for long periods as a facultative intracellular parasite. Some of the live vaccine strains can also persist for long periods in the mononuclear phagocyte system. Hosts infected in such a manner develop, in addition to a mucosal immune response, systemic cellular and serum antibody responses to the Salmonella . Thus, invading Salmonella , whether virulent or attenuated, can stimulate strong immune responses, unlike many other enteric pathogens which only set up local, noninvasive gut infections. The potent immunogenicity of live Salmonella makes them attractive candidateε for carrying parasitic helminth proteinε to the immune system. A preferred recombinant cell-based vaccine is one in which the cell is attenuated. Salmonella typhimurium strains, for example, can be attenuated by introducing mutations into genes critical for in vivo growth and survival. For example, genes encoding cyclic adenosine monophosphate (cAMP) receptor protein or adenylate cyclase are deleted to produce avirulent, vaccine strains. Such strains can deliver antigens to lymphoid tissue in the gut but demonstrate reduced capacity to invade the spleen and mesenteric lymph nodes. These strains will still stimulate both humoral and cellular immunity in mammalian hosts. Recombinant cell vaccines can be used to introduce isolated proteins of the present invention into the immune systems of animals. For example, recombinant molecules comprising parasitic helminth nucleic acid sequences of the present invention operatively linked to expression vectors that function in Salmonella can be transformed into Salmonella host cells. The resultant recombinant cells are then introduced into the animal to be protected. Preferred Salmonella host cells are those for which survival depends on their ability to maintain the recombinant molecule (i.e., a balanced-lethal host-vector system). An example of such a preferred host / recombinant molecule combination is a Salmonella strain (e.g., UK-1 v 3987 or SR-11 v 4072) which is unable to produce aspartate /3-semialdehyde dehydrogenase in combination with a recombinant molecule also capable of encoding the enzyme. Aspartate β- semialdehyde dehydrogenase, encoded by the aεd gene, is an important enzyme in the pathway to produce diaminopimelic acid (DAP) . DAP is an essential component of the peptidoglycan of the cell wall of Gram-negative bacteria, such as Salmonella , and, as such, is necessary for survival of the cell. Thus, Salmonella lacking a functional asd gene can only survive if they maintain a recombinant molecule that is also capable of expressing a functional aεd gene. The efficacy of a therapeutic composition of the present invention to protect an animal from infection by a parasitic helminth can be tested in a variety of ways including, but not limited to, detection of protective antibodies (using, for example, proteins or mimetopes of the present invention) , detection of cellular immunity within the treated animal, or challenge of the treated animal with the parasitic helminth or antigens thereof to determine whether the treated animal is resistant to infection. Such techniques are known to those skilled in the art. One preferred embodiment of the present invention is the use of D . immitiε nucleic acids and proteins to protect an animal from heartworm infection. It is particularly preferred to prevent L3 larvae that are delivered to the animal by the mosquito intermediate host from maturing into adult worms. As such, preferred therapeutic compositionε are those that are able to inhibit at least one step in the portion of the parasite's development cycle that includes L3 larvae, third molt, L4 larvae, fourth molt, immature adult prior to entering the circulatory system. In dogs, this portion of the development cycle is about 70 days. As such, preferred nucleic acid sequences, proteins, and antibodies to protect an animal against heartworm include D . immitis p4 and D . immitiε p22U, as well as nucleic acid sequences including at least a portion of D . immitiε p4 and/or D . immitiε p22U, proteins encoded by those sequences, mimetopes of such proteins, and antibodies that selectively bind to such proteins. Particularly preferred therapeutic compositions include proteins that share at least some D . immitiε P4 and/or D . immitiε P22U epitopes. Such compositions are administered to animals in a manner effective to protect the animals from heartworm infection. Additional protection may be obtained by administering additional protective compounds, including other D . immitiε antigens, such as D. immitis P39, D . immitis P22L, D. immitiε P20.5, D . immitiε Di22, and/or D. immitiε proteases expressed in L3 and/or L4 larvae. In another embodiment of the present invention, preferred nucleic acid sequences, proteins, and antibodies to protect an animal against heartworm include D . immitiε p39, D . immitiε p22L, and/or D . immitiε p20.5, aε well aε nucleic acid sequences including at least a portion of D . immitiε p39, D. immitiε p22L and/or D. immitiε p20.5, proteins encoded by those seguenceε, mimetopeε of such proteins, and antibodies that selectively bind to such proteins. Particularly preferred therapeutic compositions include proteins that share at least some D . immitiε P39 and/or D . immitiε P22L/P20.5 epitopes. Such compositions are administered to animals in a manner effective to protect the animals from heartworm infection. Additional protection may be obtained by administering additional protective compounds, including other D . immitiε antigens, such as D . immitis P4 , D. immitiε P22U, D . immitiε Di22, and/or D. immitiε proteases expressed in L3 and/or L4 larvae. It is also within the scope of the present invention to use the isolated parasitic helminth proteins, mimetopeε, nucleic acid sequences, and antibodies as diagnostic agents. Preferably εuch diagnoεtic agents are supplemented with additional compounds that can detect other phases of the helminth's life cycle. One embodiment of the present invention is a therapeutic compoεition capable of protecting an animal from parasitic helminth infection when administered to the animal in an effective manner that includes a compound capable of substantially interfering with the function of a parasitic helminth protein LDLr class A cysteine-rich motif, preferably by reducing the ability of such a protein to take up sterols. Aε used herein, a parasitic helminth protein LDLr class A cysteine-rich motif, or LDLr class A motif, refers to cysteine-rich motifs in parasitic helminth proteins that are homologous to that identified in D . immitiε P4. Such motifs also occur in several other proteins, including LDL receptor-related proteinε and α 2 - macroglobulin receptors, as heretofore disclosed. As used herein, substantially interferes refers to the ability of the compound to inhibit parasitic helminth development. Preferred therapeutic compoεitionε are thoεe that are targeted to the LDLr class A motif shared by D. immitiε P4 and other parasitic helminth proteins encoded, at least in part, by a nucleic acid sequence capable of hybridizing, under stringent conditions, to at least a portion of D . immitiε p4. Suitable compounds can be identified by a variety of methods, including known methods to screen inorganic and organic molecules and rational drug design methods in which the active site of the motif is identified and a compound designed that would interfere with that active site. Suitable compounds are likely to include sterol mimetopes that are capable of interfering with sterol uptake by parasitic helminths, possibly by selectively binding to the LDLr class A motif. Parasitic helminths, some protozoans and some insects are not able to synthesize squalenes and sterols de novo . Thus, parasitic helminths require sterols as precursors for steroid hormones and as integral structural components of cellular membranes. Cholesterol, one of the sterols that parasitic helminths cannot produce de novo, regulates cellular function, growth and differentiation by interacting with a number of protein kinases, protein receptors and ion pumps. Choleεterol is also the precursor of ecdysteroids, the steroidal molting hormones of insects, also believed to serve a similar function in parasitic helminths. While not being bound by theory, it is believed that the LDLr class A motif is important in the development of parasitic helminths (including nematodes, trematodes, and cestodes) as well as other organisms that do not synthesize sterols de novo (e.g., some paraεitic protozoans and insects) , because known LDLr class A motifs are apparently involved in sterol uptake. Such motifs in LDL receptors, for example, are responsible for binding the positively-charged ligands apolipoprotein B (apo B) and apolipoprotein E (apo E) within lipoprotein particles (see, for example, Herz et al., 1988, EMBO J . 7 , p. 4119-4127). Apo E is involved in the clearance of triglyceride-rich lipoproteins and in reverse cholesterol transport. ApoE is also thought to be involved in the modulation of cell growth in mammalian lymphocytes as well as in brain and other tissues. Thus, compounds having the ability to interfere with sterol uptake by parasitic helminths due to their ability to interact with LDLr claεε A motifs are attractive aε therapeutic compoεitionε of the present invention. Such therapeutic compositions can be administered to animals in an effective manner to protect animals from parasitic helminth infection. Effective amounts and dosing regimens can be determined using techniques known to those skilled in the art. The following examples are provided for the purposes of illustration and are not intended to limit the scope of the invention. Examples Example 1 This Example describeε a procedure for producing and evaluating immune sera of the present invention. Four dogs were immunized with chemically-abbreviated D . immitiε larval infections (using the method described in Grieve et al., 1988, ibid.), and two dogs served as chemically-treated controls. The dogs were housed in indoor mosquito-free individual cages at a temperature of about 22°C and about 40% to about 65% humidity. On day 532, post initial immunization, each dog was challenged with about 100 L3 D . immitiε larvae by implanting 5 diffusion chambers per dog, each diffusion chamber containing about 20 L3 D . immitiε larvae, using the method described in Grieve et al., 1988, ibid. Concomitant with chamber implantation, each dog was injected subcutaneously with about 50 L3 D . immitiε larvae, and the infection was allowed to proceed beyond the anticipated prepatent period. Challenge infections were repeated on day 588, post initial immunization, both by implanting 5 diffusion chamberε per dog, each chamber having about 20 L3 D . immitiε larvae and by subcutaneously inoculating about 30 L3 D . immitiε larvae per dog. Serum samples were collected from the immunized dogs at numerous time points throughout the study period. Serum samples were analyzed for antibodies that selectively bound to L3 and/or L4 surface antigenε uεing an indirect fluorescent antibody assay, and for antibodies that selectively bound to L3 soluble antigens, L4 soluble antigens and/or to an excretory/secretory antigen fraction using an indirect ELISA, as described by Grieve et al., 1988, i id. The results indicated that serum from dogs that had been immunized and challenged with D . immitiε larvae had produced antibodies to both surface and soluble D . immitis larval antigens. The sera were pooled, and those obtained from larval-immunized dogs (i.e., anti- larval immune sera) were shown to inhibit larval development; see, for example, Example 2. Immune sera were also shown to selectively bind to L3 and/or L4 larval proteins having molecular weights of about 15 kD, 23/24 kD doublet, 31 kD, 33 kD, 39 kD, 42 kD, 55 kD, 59 kD, 66 kD, 70 kD, 97 kD and 207 kD by Triε-glycine SDS PAGE. Example 2 Thiε Example demonstrates that serum collected from larval-immunized dogs, produced as described in Example 1, is capable of inhibiting parasite development whereas serum collected from non-immunized dogε is not. One subcutaneous pocket was formed in each of about 3 to about 6 Balb/C BYJ mice that were about 10 weeks old. One diffusion chamber, containing 20 L3 D . immitiε larvae, was implanted into each pocket alone with 0.5 ml of sera collected from immunized dogs or from non-immunized dogs, produced as described in Example 1. The diffuεion chamberε were recovered two or three weeks later. Living larvae in the chambers were counted and placed into glacial acetic acid, followed by 70% ethanol containing 5% glycerin. The ethanol was allowed to evaporate leaving the larvae in glycerin. The larvae were measured using projected images in the Macmeasure image analysis system on a Macintosh computer. Three experiments, in which different serum samples were exposed to larvae in diffusion chambers, were conducted: Experiment 1 compared equal portions of sera collected from individual dogs at days 56, 77 and 117 after challenge. Experiments 2 and 3 compared serum collected from immunized dogs 117 days after initial challenge to control sera. In experiment 2, the control serum was a pool of sera collected from 12 naive dogs; in experiment 3, control serum was collected from a single naive dog. Each of the experiments also included controls in which the larvae were not exposed to any serum. In experiment 1, chambers were recovered two weekε post-inoculation. The number of larvae retrieved from chambers implanted in mice receiving serum from immunized (i.e., immune) dogs waε lower than that of larvae in chambers implanted in mice receiving naive dog serum, but the difference was not statistically significant. Also, no differences were seen between the length of larvae regardless of which serum was used. In experiments 2 and 3, the chambers were recovered three weekε after infection. There were εignificant differenceε in the larval recoverieε between those receiving serum from naive dogs and those from immune dogs; there were about 34% more larvae recovered from mice treated with naive dog serum than were recovered from mice treated with immune serum. The lengths of the larvae were also significantly shorter in those chambers exposed to sera from immune dogs compared to larvae in chambers exposed to naive dog sera. Thus, thiε Example εhows that serum collected from dogs immune to D . immitiε infection inhibits larval development, compared to serum collected from naive dogs. Example 3 This Example describes the purification of D . immitiε P22U, P22L and P20.5 as well as tryptic digestion of the proteins, and partial amino acid sequencing of several tryptic fragments. Larvae and ES proteins were pulse chase labeled as described by Frank et al., 1992, J . Paraεitol . 77, 950-956. Proteins of 22 and 20.5 kD were shown to be developmentally regulated proteins that were particularly present in L3 and L4. Third εtage larvae were collected and cultured in vitro as deεcribed in Frank et al., ibid . The larvae were washed free of serum proteins at about 48 hr, placed back into culture and the serum-free media containing larval ES products was collected from 48 to 144 hr in culture. Each week's yield of ES was collected, filtered through a 0.45 μm filter (Acrodisc™, Gelman Sciences, Ann Arbor, Michigan) and frozen at about -70"C until further processing. Processing was conducted at about 4 β C or on ice and consisted of thawing the ES and adding 0.5 M EDTA-Na 2 , pH 8.0, to a final concentration of 5 mM. EDTA was the only protease inhibitor used since only metalloprotease activity has been found in larval ES (Richer et al., 1992, Exp. Paraεit . 75, p. 213-222). The ES was concentrated and the buffer was exchanged using Centriprep-10 and Centricon-10 (Amicon, Beverly, MA) ; the final buffer was 20 mM Tris, 1 mM EDTA-Na 2 , pH 7.2. All chromatography waε performed on a Beckman 338 binary system using System Gold version 3.10 chromatography software (Beckman Instruments, Inc., San Ramon, CA) . The separations and fraction collections were conducted at room temperature and the fractions placed at about 4°C immediately after each run. When portions of the samples were metabolically labeled, aliquots of the collected fractions were assayed in scintillation fluid by a Beckman Model LS 1801 liquid scintillation counter (Beckman Instruments, Inc.). The first purification was from approximately 38,650 larvae, 3,550 of which had been metabolically labeled with Translabel™ from about 48 to 144 hr. The ES products were concentrated to 175 μl in 20 mM Tris, 1 mM EDTA-Na 2 , pH 7.2 (Buffer A) and contained 1.3 μg/μl protein with an 35 S- incorporation of 7,450 cpm/μl. Cation exchange chromatography was uεed aε the first step in purification. A SynChropak CM300-GRD 4.6 x 50 mm column (Synchrom, Inc., Lafayette, Indiana) was used. The sample was diluted with 300 μl buffer A, centrifuged at 12,000 g and the supernate injected onto the column at 0.5 ml/min Buffer A. After a 5 min wash, the adsorbed proteins were eluted with a steep gradient to 100% Buffer B (1 M KCl in Buffer A) over 0.1 min while 200 μl fractions were collected throughout. Detection of proteins was at 280 nm. FIG. 1 εhowε the resultant chromatogram. Boxed fractions, designated 4, 5, 6, 23, 24, 25 and 26, were evaluated by SDS PAGE. The vast majority of contaminating proteins eluted in the initial peak. In contrast, P22U, as well as P22L and P20.5, eluted in the second peak, i.e., in fractionε 23, 24, 25 and 26. Reverse phase chromatography using a Vydac C 4 0.21 x 25 cm, 5 μm particle εize column (Vydac 214TP52, The Separationε Group, Hesperia, CA) was used to separate P22U from P22L and P20.5. Buffer C consiεted of 0.1% trifluoroacetic acid (TFA), 0.085% triethylamine (TEA) in Milli-Q water produced by proceεεing 18 megaohm water through a Milli-Q Plus water syεtem (Millipore Corp., Bedford, MA), while Buffer D conεiεted of 0.085% TFA, 0.085% TEA, 80% CH 3 CN in Milli-Q water. Detection of proteinε was at 220 nm. Fractions 23 and 24 from the cation exchange run were injected onto the column followed by fractions 25 and 26 two min later. The initial flow rate was 0.25 ml/min at 12.5% D, 87.5% C. The flow rate was reduced to 0.17 ml/min at 4 min and a gradient to 62.5% D over 200 min was started at 6 min. Fractions of 0.75 min were collected. Aliquots of peak fractions were submitted to SDS-PAGE and analyzed by silver staining and autoradiography. P20.5 appeared firεt and predominated in fractions 99-102 (elution timeε of from about 74.25 minutes through about 76.5 minutes). P22L predominated in fractions 103-107 (elution times of from about 77.25 minutes through about 80.25 minutes) , although there was significant contamination with P20.5. P22U eluted much later, in fractions 229-235 (elution times of from about 171.75 minutes through about 176.25 minutes). P22U, P22L and P20.5 recovered from C4 reverse phaεe chromatography were each εhown by immunoblot analysis (see, for example Grieve et al., 1992, J. Immunol . 148, 2511-2515 for method), uεing dog immune εerum prepared as in Example 1, to be uniquely recognized by the immune serum. The molecular weights of P22U, P22L and P20.5 were determined using Tris-tricine SDS-PAGE according to the method of Schagger and von Jagow, 1987, Analyt . Biochem . 166, 368-379. This Tris-tricine syεtem haε been reported to give more accurate eεtimateε of molecular weights for other proteins; see, for example, Patton et al., 1991, Analyt . Biochem . 197, 25-33. Molecular weight standardε used were SDS-PAGE Standards, Low Range (Bio-Rad Laboratorieε) and MW-SDS-17S (Sigma Chemical Co., St. Louiε, MO). The 20 and 22L kD proteins resolved aε 16.1 and 18.8 kD by reducing Tris-tricine SDS-PAGE. This same sample electrophoresed on 1) a εecond Tris-tricine gel resulted in molecular weights of 15.3 and 17.7 kD, and 2) a Tris-glycine gel resulted in molecular weights of 21.9 and 23 . 2 kD . Fractionε containing P22L and P20.5 obtained from C 4 reverεe phase chromatography were submitted to C 18 reverse phase chromatography using a 0.21 x 25 cm, 5 μm particle size column (Vydac 218TP52) to try to separate the two proteins further. The flow rate was 0.2 ml/min at 11.1% Buffer F (0.085% TFA, 90% CH 3 CN in Milli-Q water), 88.9% Buffer E (0.1% TFA in Milli-Q water) with a gradient to 83.3% Buffer F over 65 min. One minute fractions were collected from 3 through 83 min. P20.5 eluted first, followed by P22L. A εample of purified P22U obtained from C 4 reverεe phaεe chromatography as well aε εampleε of purified P22L and P20.5 obtained from Cι 8 reverεe phase chromatography were denatured, reduced and pyridylethylated by standard procedureε (see, for example, Matsudaira, P. T. (ed.)., 1989, A Practical Guide to Protein and Peptide Purification for Microεequencing) . The pyridylethylated P22U, P22L and P20.5 samples were each subjected to trypsin digestion, and the tryptic peptideε εeparated by C 18 reverse phase chromatography using a 0.21-cm x 25-cm, 5-μm particle size column (Vydac 218TP52) by a procedure based on Stone et al., 1989, in Matεudaira, P. T. (ed.)., A Practical Guide to Protein and Peptide Purification for Microεequencing, p. 31-47. Chromatogra s depicting the tryptic fragments of P20.5, P22L and P22U are shown in FIG. 2 , labelled, respectively as "20 kDa", "22L kDa" and "22U kDa". As seen from FIG. 2, the tryptic map of P22U iε completely different from thoεe of P22L and P20.5, which share at least some fragmentε in common. Fragments indicated by asterisks were submitted for sequencing. All sequencing was conducted at Macromolecular Resources, Department of Biochemistry, Colorado State University, Fort Collins, CO. The peptides were concentrated to 50 μl or leεs using a Speedvac ® and frozen at about -20°C until seguencing. N-terminal sequencing was conducted in an ABI Model 473A Protein/Peptide Sequencer System (Applied Biosyεtems, Inc., Foεter City, CA) uεing pulsed liquid chemistry and on line microgradient PTH amino acid analysis (see, for example, Hewick et. al., 1981, J. Biol . Chem . 256, p. 7990-7997; Geisow and Aitken, 1989, in Findlay, J.B.C. and M.J. Geisow (ed.). Protein Sequencing: A Practical Approach , p. 85-98) . N-terminal amino acid sequencing of electroblotted P22L and P20.5 was conducted as originally described by Matsudaira, 1987, J . Biol . Chem . 262, 10035-10038, and outlined by LeGendre et al., 1989, "A Practical Guide to Protein and Peptide Purification for Microεeguencing," Matεudaira, P.T. (ed.), pp. 49-69. P20.5 yielded sequence while P22L was determined to be N-terminally blocked. The most likely sequence of the P22U tryptic fragment eluting at 44 minutes (referred to as the 44 min P22U tryptic fragment) , using one-letter amino acid code, was MAQDAFPNACAQGEPK. The most likely sequence of the P22U tryptic fragment eluting at 58 minutes (referred to as the 58 min P22U tryptic fragment) was AIAPCQLTAVQSVLPCADQCQK. The most likely seguence of the P22U tryptic fragment eluting at 60 minuteε (referred to as the 60 min P22U tryptic fragment) was LGSCSPDCGLDLPSDNVMVQDV. The most likely seguence of the P22L tryptic fragment eluting at 35 minutes (referred to as the 35 min P22L tryptic fragment) was HVETHEACYDQR. The most likely seguence of the P22L tryptic fragment eluting at 38 minutes (referred to as the 38 min P22L tryptic fragment) was GEFVESDGK. The most likely seguence of the P22L tryptic fragment eluting at 44 minutes (referred to as the 44 min P22L tryptic fragment) was N-WQCSYD. The moεt likely sequence of the P22L tryptic fragment eluting at 58 minutes (referred to as the 58 min P22L tryptic fragment) was EPQSWCILKPHQS-TQR. The most likely sequence of the N-terminus of P20.5 was ETQEETV-FEE-D-D. The most likely sequence of the P20.5 tryptic fragment eluting at 31 minutes (referred to as the 31 min P20.5 tryptic fragment) was FVESDGK. The most likely εeguence of the P20.5 tryptic fragment eluting at 32 minuteε (referred to aε the 32 min P20.5 tryptic fragment) waε T-EACYDQR. The most likely sequence of the P20.5 tryptic fragment eluting at 42 minutes (referred to as the 42 min P20.5 tryptic fragment) was FNWQCSYD. Example 4 This Example describes the cloning and sequencing of D . immitis nucleic acid sequence p4. D . immitiε p4 was identified by itε ability to encode a protein that selectively bound to at least one component of immune serum collected from a dog immunized with D . immitis larvae. D . immitiε L3 larvae were harvested from mosquitoε using standard technigues and cultivated in vitro in 50:50 NCTC-135/IMDM (NI) media (Sigma) supplemented with 20% serum supplement at 37°C, 5% carbon dioxide for 48 hours. Total RNA waε extracted from the larvae using an acid- guanidinium-phenol-chlorofor method similar to that described by Chomczynski and Sacchi, 1987, Anal. Biochem . 162, p. 156-159. Approximately 15,000 to 30,000 larvae were used in an RNA preparation. Poly A+ selected RNA was separated from total RNA by oligo-dT cellulose chromatography using Oligo dT cellulose from Collaborative Research, Inc. , Waltham, MA, according to the method recommended by the manufacturer. A D . immitis L3 larval cDNA expression library was constructed in lambda (λ) Uni-ZAP™ XR vector (available from Stratagene Cloning Systems, La Jolla, CA) using Stratagene's ZAP-cDNA Syntheεiε Kit ® protocol and about 5 μg to about 6 μg of L3 poly A+. The reεultant library waε amplified to a titer of about 4.88 x 10 9 pfu/ml with about 97% recombinants. Using the protocol described in the Stratagene picoBlue immunoscreenmg kit, the L3 larval cDNA expression library was screened with immune dog serum prepared as described in Example 1. Antibodieε εpecific for a highly immunoreactive protein termed the "ladder protein" (Culpepper et al. , 1992, Mol . Biochem . Parasitol . 54, p. 51-62) had been adεorbed from this εerum by affinity chromatography with a recombinant GST-ladder fu ion protein. Immunoεcreening of duplicate plague liftε of the cDNA library with the εame εerum identified 4 poεitive cloneε, one of which included D . immitis nucleic acid εequence p4. The remaining 3 cloneε were shown to encode at least portions of P39 and are described in greater detail in Example 8. The plaque-purified clone including D . immitiε nucleic acid sequence p4 was converted into a double stranded recombinant molecule, herein denoted as p3gal-p4, using R408 helper phage and XLl-Blue E . coli according to the in vivo excision protocol described in the Stratagene ZAP-cDNA Syntheεiε Kit. Double εtranded plaεmid DNA was prepared using an alkaline lysis protocol, such as that deεcribed in Sambrook et al., ibid . The plaεmid DNA waε digeεted with -ScoRI and Xhol reεtriction endonucleaεeε to releaεe two D . immitiε DNA fragmentε of about 580 and 320 nucleotides, the entire D . immitiε p4 fragment being about 900 nucleotides in size. A p4 nucleic acid probe detected specific D . immitiε genomic DNA restriction fragments on a Southern blot verifying the D . immitiε origin of the p4 cDNA clone. The plasmid containing D . immitiε p4 was sequenced using the Sanger dideoxy chain termination method, aε deεcribed in Sambrook et al., ibid . The Promega Eraεe a Base method (available from Promega Corp., Madison, WI) was used to generate deletion clones for sequence analysis. An about 913-nucleotide consensus sequence of the entire D . immitiε p4 DNA fragment was determined and is preεented as SEQ ID N0:1. The entire 913 nucleotides form an open reading frame encoding an amino acid sequence of about 303 amino acids, presented in SEQ ID NO:2. The first ATG codon within this sequence spanε nucleotideε from about 417 through about 419. As such, SEQ ID N0:1 does not encode a full-length protein, but does encode a protein that selectively binds to at leaεt one component of immune dog εerum. The predicted size of the protein encoded by SEQ ID NO:l is about 35.5 kD, with an estimated pl of about 4.26. A homology search of the non-redundant protein sequence database was performed through the National Center for Biotechnology Information using the BLAST network. This database includes SwissProt + PIR + SPUpdate + GenPept + GPUpdate. The εearch waε performed using SEQ ID NO:2 and showed the only significant homology shared between SEQ ID NO:2 and known seguences to be a contiguous stretch of 9 amino acids, namely DDCGDGSDE, that was also found in human LDL-receptor related protein, human and mouse alpha-2- macroglobulin receptors and rat renal GP 330 glycoprotein. A conserved stretch of eight of the nine amino acids iε alεo found in Caenorhabditiε eleganε LDL receptor-related protein and C. eleganε basement membrane proteoglycan. Example 5 This Example demonstrates the ability of D . immitiε p4 to encode a protein that εelectively binds to immune serum. The recombinant protein iε alεo capable of generating an immune response in rabbits. Recombinant molecule pET19b-p4 635 , containing!), immitiε p4 nucleotides from about 1 through about 635 operatively linked to bacteriophage T7lac transcription control sequences and to a fusion sequence encoding a poly- hiεtidine segment comprising 10 hiεtidineε waε produced in the following manner. An about 635-nucleotide DNA fragment containing nucleotideε εpanning from about 1 through about 635 of SEQ ID N0:1, called p4 635 , was PCR amplified from a clone containing D . immitiε p4 using the primerε 5' CGGGATCCCG AGTTAAATAG TCG 3' (denoted 394-5'; BamHI εite underlined) and 5' TGCAGGATCC TGCACCG 3' (denoted 394-3'; BamHI site underlined) . The PCR product was digested with BamHI restriction endonucleaεe, gel purified and εubcloned into expreεεion vector pET19b (available from Novagen Inc., Madiεon, WI) that had been cleaved with BamHI. The resulting recombinant molecule pET19b-p4 635 was transformed into E . coli BL21(DE3)pLysS to form recombinant cell E . co!i:pET19b-p4 635 . E. coli BL21(DE3)pLysS includeε a bacteriophage T7 RNA polymeraεe gene under the control of lac tranεcription control sequences. Recombinant cell E. coli:pET19b-p4 635 was cultured in shake flaskε containing an enriched bacterial growth medium containing 0.1 mg/ml ampicillin and 0.034 mg/ml chloramphenicol at about 37°C. When the cellε reached an optical density at about 600 nanometers (OD 60 o) of about 0.819, expression of D . immitis p4 was induced by addition of about ImM isopropyl-/3-D-thiogalactoεide (IPTG) . Protein production waε monitored by SDS PAGE of recombinant cell lysates, followed by Coomassie blue staining, using standard techniques. Recombinant cell E . coli:pET19b-p4 635 produced a protein, denoted PHIS-P4 635 , that migrated with an apparent molecular weight of about 37 kD. Such a protein was not produced by cells transformed with the pET- 19b plasmid lacking a D . immitiε DNA inεert. Immunoblot analysis of recombinant cell E . coli:pET19b-p4 635 lysates indicates that the 37 kD protein iε able to selectively bind to immune dog serum and, as such, iε capable of binding to at least one component of a serum that is capable of inhibiting D . immitis larval development. The E. coli:pETl9b-p4 635 histidine fuεion peptide waε separated from soluble E. coli proteins by nickel chelation chromatography and an imidazole gradient. Immunoblot analysis of the total E. coli:pET19b-p4 635 lysate, column eluate and column void volume indicates that the 37kD protein can be isolated on the nickel column and is able to selectively bind to immune dog serum, and as such, is capable of binding to at least one component of a serum that is capable of inhibiting D . immitis larval development. The column eluate was not detected by preimmune sera from the same immune dog. A rabbit waε immunized with recombinant PHIS-P4 635 according to standard techniques, such as those heretofore disclosed. Antibodies collected from the immunized rabbit were capable of binding to formic acid-cleaved PHIS-P4 635 , indicating that the antibodies were capable of detected unfused P4 635 . Example 6 This Example deεcribeε the isolation and sequence of D . immitiε nucleic acid sequence p22U. Total RNA was extracted from adult female D . immitiε worms, poly A+ RNA prepared, and an adult female D . immitiε cDNA library produced, using methods similar to those described in Example 4. A segment of DNA for uεe in the identification of a nucleic acid sequence capable of encoding at leaεt a portion of P22U was produced by PCR amplification using standard techniques, such aε those described in Sambrook et al., ibid . Briefly, first strand cDNA was syntheεized from adult female poly A+ RNA uεing Murine Leukemia Viruε reverεe tranεcriptaεe (available from Stratagene) and Stratagene'ε linker-primer from their ZAP-cDNA Synthesis Kit, namely 5' GAGAGAGAGA GAGAGAGAGA ACTAGTCTCG AGTTTTTTTT TTTTTTTTTT 3'. A pool of two setε of degenerate primerε was produced based on the partial amino acid seguence of the 60 min tryptic fragment described in Example 3. One degenerate εet of primers, denoted GRF 11, includes the following sequences: 5'TGY TCN CCN GAY TGY GG 3' , wherein Y can be either C or T, and N can be either A, G, C or T. The second set of primers, denoted GRF 12, includes the following seguenceε: 5'TGY AGT CCN GAY TGY GG 3'. PCR amplification using the pool of degenerate primers in combination with Stratagene's linker-primer aε the antisense primer was used to amplify the DNA segment. Verification that the appropriate segment had been amplified was accomplished by Southern blot analysis using a degenerate probe based on a more C-terminal amino acid εequence of the 60 min tryptic fragment, namely GRF 3 which includes the following sequenceε: 5' TGN ACC ATN ACR TTR TC 3', wherein R can be either A or G. The amplified segment was gel purified, electroeluted and cloned into the pCR II cloning vector (available from Invitrogen, San Diego, CA) , following the manufacturers' instructionε. Two clones were partially sequenced, yielding a nucleic acid sequence which included a sequence corresponding to the amino acid sequence of the 60 min tryptic fragment. The nucleic acid sequence includes from nucleotides about 444 to about 696 of SEQ .ID NO:3, described in more detail below. The adult female cDNA library was screened with an antisense probe, using stringent (i.e., standard) hybridization conditions as described in Sambrook et al. , ibid. . The antisense probe, denoted GRF14, was based on the DNA sequence derived from the amplified segment and has the sequence 5' CTGTTTGAAC CATAACATTA TCAGATGG 3'. Plaques which hybridized to the probe were rescreened, plaque purified and clones containing D . immitiε nucleic acid sequence p22U (i.e., clones that hybridized with the antisenεe probe and having the apparent nucleic acid sequence designated in SEQ ID NO:3) were εubmitted to nucleic acid sequencing as described in Example 4. An about 1016-nucleotide consensus sequence of D . immitis nucleic acid sequence p22U was determined and is presented as SEQ ID NO:3. The deduced translation product is presented both with SEQ ID NO:3 and in SEQ ID NO:4. SEQ ID NO:3 apparently encodes a protein of about 208 amino acids, the sequence including a stop codon εpanning nucleotideε about 627 through about 629. There are two ATG codons spanning nucleotides about 39 to about 41 and spanning nucleotides about 57 to about 59. Although SEQ ID NO:3 encodeε a protein of about the expected εize (i.e., predicted size of about 22 kD) , the actual translation initiation site of the protein is aε yet unknown. Nucleic acid εequenceε encoding all three partially sequenced tryptic peptides are included in SEQ ID NO:3, indicating that the sequence does encode at leaεt a portion of P22U. The portion of the 44 min tryptic fragment that was sequenced spans amino acidε about 77 to about 92 of SEQ ID NO:4 and agrees with the derived seguence in all but one amino acid. The portion of the 58 min tryptic fragment that was seguenced spanε amino acids about 27 to about 48 of SEQ ID NO:4 and agrees with the derived εequence in all but one amino acid. The portion of the 60 min tryptic fragment that waε εeguenced εpans amino acids about 145 to about 166 of SEQ ID NO:4 and agrees with the derived sequence in all but one amino acid. A homology search of the non-redundant protein sequence database was performed through the National Center for Biotechnology Information using the BLAST network. This database includes SwissProt + PIR + SPUpdate + GenPept + GPUpdate. The search was performed using SEQ ID NO:4 and no significant homology with known proteins was indicated. Example 7 This Example demonstrates the ability of D. immitis p22U to encode a protein that selectively binds to immune serum and to antibody against native p22U. Recombinant molecule pHis-p22U 60 8/ containing D. immitis p22U nucleotides from about 41 through about 649 operatively linked to trc transcription control seguenceε and to a fuεion seguence encoding a poly-histidine segment comprising 6 histidines was produced in the following manner. An about 608-nucleotide DNA fragment containing nucleotides spanning from about 41 through about 649 of SEQ ID NO:3, called p22U 60 β/ was PCR amplified from a clone containing D . immitiε p22U using the primers 5' GTTGCAATAT GGGATCCAAT GAGCC 3' (denoted 22USEN; BamHI site underlined) and 5' CGCTAGTGCA GGATCCTCAA TACTC 3' (denoted 22UANT; BamHI site underlined) . The PCR product was digested with BamHI restriction endonuclease, gel purified and subcloned into expression vector pTrcHisB (available from Invitrogen) that had been cleaved with BamHI. The reεulting recombinant molecule pHis-p22U 608 was transformed into E . coli to form recombinant cell E . coli:pHis-p22U 60 s. The recombinant cell was cultured in shake flasks containing an enriched bacterial growth medium containing 0.1 mg/ml ampicillin at about 37°C. When the cells reached an OD 600 of about 0.3, expression of D . immitiε p22U 60 s was induced by addition of about 1 mM IPTG. Protein production was monitored by SDS PAGE of recombinant cell lysates, followed by Coomassie blue staining, using standard techniques. Recombinant cell E . coli:pHiε-p22U 608 produced a protein, denoted herein aε PHIS-P22U 60 s, that migrated with an apparent molecular weight of about 27 kD. Such a protein waε not produced by cellε tranεformed with the pTrcHisB plasmid lacking a D. immitiε DNA insert. Immunoblot analysis of recombinant cell E. coli:pHis- p22U 608 lysates indicates that the 27-kD protein is able to bind to immune dog serum and, as εuch, iε capable of binding to at leaεt one component of a εerum that iε capable of inhibiting D . immitiε larval development. Immune dog serum essentially does not bind to lysates of cells transformed with only the pTrcHisB plasmid. Cats have been immunized with PHIS-P22U 608 according to εtandard protocols. Native D. immitiε P22U was purified and uεed to immunize a rabbit for reagent antibody. Antiεera collected from the immunized rabbit detected both native 22U protein from 6 day L4 larvae and PHIS-P22U 608 recombinant protein by Weεtern blot. Example 8 This Example deεcribeε the cloning and εequence of D . immitiε nucleic acid εequence p39. D . immitiε p39 waε identified by its ability to encode a protein that selectively bound to at least one component of immune serum collected from a dog immunized with D. immitiε larvae. Genomic and cDNA expression libraries in λZapII (Short, J.M., et al., 1988, Nucleic Acidε Reε 16:7583- 7600) , a derivative of λgtll, were prepared from total genomic DNA, or L4 or L3 larval stage mRNAε, respectively, using standard procedures (Short Protocolε in Molecular Biology, 1989, Ausubel, M.F., et al. , eds.). In thiε example, four cDNA expreεεion librarieε were prepared from D. immitiε adult female, adult male, 48 hour third εtage (L3) , and 6 day fourth stage (L4) larvae mRNA in lambda (λ) Unizap XR vector (Stratagene) using the Zap-cDNA synthesis kit ® protocol (Stratagene) in a manner similar to that described in Example 4. For each library approximately 5-6 μg of mRNA was used. The resulting libraries were amplified one time and the titers were: Adult male: 1.15 x 10 10 pfu/ml with 99% recombinants; Adult female: 1.4 x 10 9 pfu/ml with 97% recombinants; 48 hour L3 larvae: 4.88 x 10 9 pfu/ml with 97% recombinants; 6 day L4 larvae: 1.05 x 10 9 pfu/ml with 98% recombinants. These libraries were screened with pooled immune dog sera in a manner similar to that described in Example 4. The 48 hour L3 library was screened with immune dog serum prepared aε deεcribed in Example 1 due to its almost exclusive reactivity with the 39 kD protein. Antibodies specific for a highly immunoreactive protein termed the "ladder protein" had been adsorbed from this serum by affinity chromatography as described in Example 4. Development of immunoblots containing adult female worm, and L3 or L4 larval protein lysates with the adsorbed sera showed reactivity to the previously recognized 39 kD protein and one other >100 kD protein only in the larval lysates. Immunoscreenmg of duplicate plaque lifts of the 48 hour L3 library with thiε sera identified 4 positive clones named p39-l through p39-4. p39-4 has been renamed p4 and is described in greater detail above. p39-l, p39-2 and p39-3 each represent p39 nucleic acid sequences that encode P39 proteinε as defined herein. An antibody select technique (Hall et al., 1984, Nature 311, 379-382) was used to obtain clone-specific antibodies for p39-l and p39-3. Using the protocol described for library immunoscreenmg, two 90 mm agar plates, each containing 1.5 x 10 4 purified phage were overlaid with nitrocellulose filters, previously soaked in 10 mM IPTG. The plaque lifts were incubated overnight in immune dog sera prepared as described in Example 1 diluted 1:200 in TBS-1% gelatin, and washed 4X in TBST (20 mM Tris- HCl, pH 7.5, 150 mM NaCl, 0.05% Tween-20) and 2X in TBS (TBST without the Tween-20) . Like filters were treated with 2.0 ml glycine buffer (0.1 M glycine-HCl, pH 2.6, 0.15 M NaCl) for 15 minutes on ice to elute clone-specific antibodies. The acidic eluate was immediately neutralized by the dropwise addition of 1 M Tris, pH 8.0. The clone- specific antibodies were concentrated in an Amicon centricon 30 microconcentrator and used to develop immunoblots of D. immitiε adult female, and L3 and L4 larval proteinε. Clone-specific antibodies eluted from clones p39-l and p39-3 detected a single 39 kD larval specific protein that migrated at the same position as the larval 39 kD native protein selectively bound by immune dog serum. Antibodies selected from a non-recombinant phage showed no reactivity to the D . immitiε proteins. These data indicate that these p39 recombinant clones encode the 39 kD protein selectively detected by immune dog sera. The clones identified as immunoreactive with the immune serum provide a source of DNA encoding desired proteins. Double stranded plasmid DNA of clones p39-l, p39-2 and p39-3 was prepared as deεcribed in Example 4. Plasmid DNAs containing p39-l and p39-2 were digeεted with -5coRI and Xhol reεtriction endonucleases to releaεe two D . immitiε DNA fragmentε of about 1000 and about 200 nucleotides, the entire D . immitiε fragments each being about 1200 nucleotides in size. Digestion of plasmid DNAs containing p39-3 with -EcoRI and Xhol restriction endonucleaεes released two D . immitiε DNA fragments of about 1000 and about 60 nucleotides, the entire D. immitiε fragment being about 1060 nucleotideε in size. Double stranded p39-l, p39-2 and p39-3 nucleic acid sequences were sequenced as described in Example 4. p39-l and p39-2 include the following nucleic acid seguence (deduced start and stop codons underlined) : GTTGTGCTTC TCAACTTTGT CAAATATGCT AATGAGCGAA TACGTCGTGT TGTTTCATCT GAAGTTATTA CTAAAATGAC TGCTGGTATG AACATCCGTC TCAATTGCAC TGACATTCGG CGTAGGTTAA GAGGAATGTT TGTATCGGAA GTACTTACGA ATTGGTTTTC GTTGGGTGAA CTGAAATTTG AATTCCCTGT TGAGCAAATG AGATCATGAT AGATTTGAAG AAGATTGTGG ATGATGAATA TAACATTGAT GTGAAGCCTG ATAAAAATGG CATTGAAGAG AAGAAAGTGA TAGAACTGGA AACGCAGAAT GTGCGGAATG ATGTAGATAA AATTGATAGC GATGATGATG ACTTCCCTGA ATATGAAATT CCTGCAGGAG AATTGATTCT GAAAAAGGAA GAAAATGATG AAGAATATCG CTGTGTAGAA ATCCCATATT ATATTAGGGA TTGTATTGAG TTGCTCAATG AGCAGAATGA TTGTGCCAAA TTTGAGGCTG CATTCAATGC TCTGAAACCA ATGATTAGAC GACGAGCTGT TGGTTATGAA CAATCCGCGG AAGAACTACT CTGCCGACTT ATTGATCTTA GTGATCGCTT CAAAATTGAA CATTTCCAGG AGAAGCGACT ACAGCTTATT GAATCATGTC TAGTGACGAG TCCTTATCTG GGAAATGTAG CTATTGATGT CATGTTTTCG AGAAAATGTT CAATGATGAA TAGATATATC GTTTTAAAGG CTCTATCAGA TGCGGCGTCA GAATATTCAT CTCCAGCCGG AATTGTCGAA AATCCAGCCA TCGAAATTCC AAAAAACGGA GGTGATGTTG AAGGGCATGT CTCTCTCTGC GATGGCGATG GAAAACTGAT CTCCAAGACA AAACTTTTCG TGAGAGCACC AATTACGATG TTAAAGGAAA ACAGATTTAC ACCAATAGCA AATTCCTTCT TCTATCCCTT GACTGCAATC GATCAGCATC GTGAACATCT TGATCTCATT GGGAGAGATT CGGAATTACT GAGTAAGATT CTTTTCTGTA TGGCTCATTT GATCAAATGT TCTGGCACTT CTCCATGTAC GCTTAGAATG TGTAGGTATG TTGACTGAAT GGAACTGTTG GCTTGTCTTT CAATTTTAGA TAATTGTAAA GTTTGCCAAA ATAAAATTTG AGTTA. p39-3 is similar to p39-l and p39-2 except that p39-3 lacks the first 125 nucleotides of p39-l and p39-2 and has an additional "A" after nucleotide 203 (referring to the numbering of the p39-l and p39-2 sequences) . All three p39 nucleic acid sequences appear to encode a protein of about 300 amino acids, having a start codon spanning about nucleotides 216 through 218 and a stop codon spanning about nucleotides 1116 through 1118 (referring to the same sequences) . The deduced amino acid sequence of the P39 protein is reported above. Example 9 This Example demonstrateε the ability of a D. immitiε p39 nucleic acid εequence to encode a protein that selectively binds to immune serum. Proteins encoded by DNA inserted in frame into the _5coRI site of pBluescript expression vector, as described in Example 8, have an additional 4 kD of beta galactosidase peptide attached to the N-terminus upon induction with IPTG. This peptide iε encoded by the vector and allows for purification of the resulting fusion protein by affinity chromatography. E . coli cultures of each p3 clone were induced with IPTG to determine the size and quantity of fusion protein produced by each clone. Samples were collected prior to induction, and at 1 hour, 2 hours, 3 hours and 4 hours after induction. Clones p39-l and p39-3 encoded fusion proteins of about 40 to about 43 kD, although p39-3 led to the production of more protein per cell weight than did p39-l as evidenced by Coomassie blue straining of proteins separated by SDS-PAGE. To verify the P39 fusion protein detected by SDS-PAGE reacted with the immune dog sera used to originally isolate the clones, a western blot containing either the p39-l or the p39-3 E. coli lysates was developed with immune serum produced as in Example 1. A protein of about 40 to about 43 kD was detected in lysates of both clones but not in a nonrecombinant pBlueεcript lyεate. Example 10 This Example also demonstrates the ability of a D . immitis p39 nucleic acid sequence to encode a protein that selectively binds to immune serum. Furthermore, monospecific antibodies that are selected by their ability to bind to the recombinant P39 protein are also capable of binding to 39 kD L3 and L4 antigens. Rabbits, catε and dogε have been immunized with thiε recombinant P39 protein. Recombinant molecule pHi8-p39 900 , containing D. immitis p39-l nucleotideε from about 216 through about 1118 (referring to numbering in p39-l and p39-2 nucleic acid seguences presented in Example 8) were operatively linked to trc transcription control εequenceε and to a fu ion sequence encoding a poly-histidine segment comprising 6 histidineε was produced in a manner similar to that described for the production of recombinant molecule p22U 608 in Example 7. Briefly, the specified p39 nucleic acid sequence was PCR amplified from a clone containing D . immitis p39-l and the product subcloned into expression vector pTrcHisB. The resulting recombinant molecule, pHis- P39 900 , was transformed into E . coli to form recombinant cell E. coli:pHis-p39 900 for details, see Example 11. The recombinant cell was cultured and induced as described in Example 7. Protein production was monitored by SDS PAGE of recombinant cell lysates, followed by Coomassie blue staining, using standard techniques. Recombinant cell E. coli:pHiε-p39 00 produced a protein, denoted herein as PHIS- PS9 900 , that migrated with an apparent molecular weight of about 46 kD. Such a protein was not produced by cells transformed with the pTrcHisB plasmid lacking a D. immitiε DNA insert. Immunoblot analysiε of recombinant cell E. co2i:pHis- p39 900 lysateε indicateε that the 46-kD protein waε able to selectively bind to immune dog serum and, as εuch, waε capable of binding to at leaεt one component of a εerum that is capable of inhibiting D . immitiε larval development. Immune dog serum essentially did not bind to lysates of cells transformed with only the pTrcHisB plasmid. Purified PHIS-P39 90 o fusion protein was incubated with immune dog sera produced aε in Example 1, the monoεpecific antibodies eluted from the protein and reacted with Western blots of D . immitiε life stage specific antigens. The clone-specific antibodies recognized a 39 kD larval-specific antigen in 0 hr L3, 48 hour L3, and 6 day L4 antigen preparations but did not detect this protein in adult male, female or microfilaria preparationε. These data verify the 39 cDNA encodeε a larval specific 39 kD protein recognized by immune dog sera. A rabbit and 2 dogs have been immunized with the PHIS-P39 900 fusion protein using standard protocols, such as those disclosed above. Cats have also been immunized with the PHIS-P39 90 o fusion protein. Example 11 Thiε Example demonεtrateε the production of a P39 protein in eukaryotic cells aε well aε the production of a recombinant viruε particle vaccine capable of expreεsing P39. A PCR product waε generated from p39-3 Unizap XR phage DNA (see Example 8) using primers 39CT (5' CGCGGATCCC GCAAATGAGA TCATG3') and 39COOH (5' GCCAACGGAT CCATTCAGTC AACATACC3'), which have BamHI sites (underlined) incorporated into the primers. This approximately 900 bp PCR product was digested with BamHI and subcloned into a BamHI digested, CIP (calf intestine phosphatase)-treated pTrcHiεB vector (available from Invitrogen) . Proper 5' to 3' orientation of the p39 inεert within the vector waε verified. Thiε clone iε referred to as pHis-p39 900 . An Xhol reεtriction εite waε added to a pSP64 vector (available from Promega) by linearizing pSP64 with Smal , ligating an Xhol linker to one end, and recircularizing the vector with T4 DNA ligase to form pSP64-Xho. The pSP64-Xho vector was digeεted with BamHI, CIP-treated and ligated in the appropriate orientation to the BamHI fragment containing the p39 εequence cleaved from pHiε-p39 90 o« The resultant molecule is referred to as p76-80.B3. In order to subclone p39 into baculovirus or Sindbis expression vectors, p39-containing fragments were PCR amplified from p76-80.B3 DNA using an antisense. primer 76-58.B (5' GTGGAATTGT GAGCGG3') homologous to pSP64 located downstream of the p39 sequence and an N-terminal primer designed from p39 sequence with modifications to enhance expression in the individual syεtemε. Specifically, the N-terminal primer 105-47.A (5' GCGGGATCCT ATAAATATGA TAGATTTGAA GAAG3' having a BamHI site (underlined) ) was used to generate a p39-containing PCR product (referred to as BVp39) for subcloning into the baculovirus shuttle plasmid BlueBacIII (available from Invitrogen). An N-terminal primer 105-08.A (5' GCTCTAGACC ATGATAGATT TGAAGAAG3' having an XJbal site (underlined)) was used to produce a p39-containing PCR product (referred to as SVp39) for subcloning into the Sindbis virus shuttle plasmid Toto2Jl-minus. In order to produce a baculovirus recombinant molecule capable of directing the production of P39 90 o, BVp39 was digested with BamHI and ligated into the unique BamHI site of BlueBacIII (available from Invitrogen) shuttle plasmid. The orientation of the insert was verified and the resultant recombinant molecule designated pl05-72.5C. This recombinant molecule and linear Baculogold baculovirus DNA (available from Pharmingen, San Diego, CA) were cotransfected into Spodoptera frugiperda Sf9 host cells (donated by the Colorado Bioprocessing Center, Fort Collins, CO) to form S . frugiperda:pl05-72.5C. The recombinant virus, denoted 105-92.1, was verified for proper insert orientation and cultivated for increased production of recombinant virus and to verify expresεion of PSΘrøo by Western blot. Immunoblot analysis indicates that P39 900 produced using baculovirus vectors is capable of being selectively bound by immune sera. In order to produce a recombinant virus particle vaccine in which P39 0 o expression is under the control of a Sindbis virus promoter, SVp39 was directionally ligated into the XJbal and Xhol restriction siteε of Sindbiε virus vector Toto2Jl following removal of the chloramphenicol acetyltransferse (CAT) gene from thiε location in the vector. The resulting recombinant molecule is denoted P105-42.1A. Note that Toto2Jl is a Sindbis virus expression vector that contains the SP6 RNA polymeraεe promoter and the entire Sindbiε viruε genome through to the Nsil restriction site at nucleotide 11452 (i.e., each of the nonstructural polypeptide genes, the subgenomic promoter, and each of the structural polypeptide genes) ligated to an Sspl (nucleotide position 7499) /SstI restriction fragment from TRCAT62 which contains the subgenomic promoter, 14 nucleotides of the 5' untranslated sequence of the subgenomic mRNA, the CAT gene, 62 nucleotides of Sindbis viruε 3' untranslated sequence, and the Sindbiε virus poly-A sequence (εee Xiong et al., 1989, Science 243, 1188-1191). Recombinant molecule pl05-42.lA was linearized by digestion with Mlul , infectious recombinant Sindbis transcripts generated with SP6 RNA Polymerase and used to infect BHK (baby hamster kidney) host cells using techniques as described in Xiong et al., ibid , thereby forming BHK:pl05-42.1A. The resulting recombinant virus (denoted 105-71.1) was cultivated for increased production and is analyzed for expression by Western blot. Immunoblot analysis indicates that P39 90 o produced by this recombinant virus is capable of being selectively bound by immune εera. The infectiouε recombinant viruε can be uεed aε a live vaccine or in an expression system to produce P39. Example 12 This example describeε the cloning and εequencing of p22L and p20.5 nucleic acid εequenceε. Oligomeric DNA primers and probes were made by DNA Express, Department of Biochemistry, Colorado State Univerεity. Synthesis was done using an ABI model 392 DNA/RNA synthesizer using cyano-ethyl-phosphoramidite chemistry. Products were purified using low pressure reverse phase chromatography. Nucleic acid oligonucleotide probes were 3'-end labeled by tailing with ( 32 P)- deoxycytidine as described by Collins and Hunsaker, 1985, Analyt . Biochem . 151, 211-224. Terminal deoxynucleotidyl transferase (available from Promega Corp.) was used according to manufacturers instructionε. A 48-hour L3 cDNA library constructed from poly A+ selected RNA using the ZAP-cDNA ® Synthesis Kit and the Uni- ZAP XR vector (both available from Stratagene) was produced as described in Example 4. The final library contained about 4.88 x 10 6 plaque forming units (pfu)/μl with 96.4% recombinants. Library plating and plaque lifts were essentially done according to manufacturer's instructionε (Stratagene) using XLl-Blue Escherichia coli ; see also Sambrook et al., ibid . Plaques lifted onto Nytran 0.45 μm 137 mm membranes (available from Schleicher and Schuell, Keene, New Hampshire) were hybridized under stringent conditions (see Sambrook et al., iJid.) with about 5 pmoles of labeled GRF6 probe (approximately 1.5 x 10 6 cpm/ml) . This probe was syntheεized baεed on the amino acid εequence EACYDQ obtained from the 32 and 35 min tryptic peptideε of the P20.5 and P22L proteins, respectively, described and shown in Example 3. The DNA sequence of GRF6 was 5' GAA GCI TGC TAT GAT CAA 3', where I is inosine which is capable of base pairing with all four baseε. The wobble baεe selection for glutamic acid (E) , cysteine (C) , tyrosine (Y) , aspartic acid (D) and glutamine (Q) was based on codon usage for two D . immitiε proteins previously reported (GenBank accession numbers M29733 and M82811) . Of about 102,000 plaqueε screened, approximately 252 (0.25%) hybridized to the probe. Sixteen plugs containing poεitive plaqueε were removed and 5 of theεe were plaque purified uεing εtandard techniqueε. Double stranded plasmid DNAs of clones containing p22L or p20.5 nucleic acid sequences were prepared as described in Example 4 and εubmitted to restriction enzyme cleavage by £σoRI and Xhol restriction endonucleases. Insert sizeε were estimated to be 334 bp (clone 1) , 442 bp (clone 2) , 603 bp (clone 3) , 589 bp (clone 4) and 442 bp (clone 5) , 32 bp of which were vector sequence. DNA sequencing of the clones was accomplished as described in Example 4. Partial DNA sequence was determined for clones 1, 2 , 3 and 5 and the full double strand sequence of the protein coding region was determined for clone 4. The nucleic acid εequenceε of the coding regions of p22L and p20.5 as well aε the deduced amino acid sequences of P22L and P20.5 are presented above. (MacVector™ version 3.5 sequence analysis software (International Biotechnologies, Inc., New Haven, Connecticut) was used for amino acid translations, protein molecular weight and isoelectric point calculations, and hydrophilicity calculations) . FIG. 3A shows a hydrophilicity plot of the amino acid sequences deduced for P22L and P20.5. Hydrophilicity was calculated based on the method of Kyte et al., 1982, J . Mol . Biol . 157, 105-132, with a window size of 7 amino acids. Molecular weights, iεoelectric points (pi) and amino acid compositions of the entire P22L sequence (FIG. 3B, 22L kD) and the proposed P20.5 cleavage product beginning at the glutamic acid at position 22 (FIG. 3C, 20 kD) are shown. The protein encoded by p22L is very hydrophilic with the exception of the N-terminal 21-amino acid hydrophobic leader that is apparently cleaved from P20.5. The calculated molecular weight of this 21 amino acid segment is 2.2 kD. This relationεhip between P22L and P20.5 explains both the similar chromatographic behavior and the similar immunological reactivity of the two molecules. The calculated molecular weight and pi of P22L are 17,527.7 and 4.58, respectively, while those for P20.5 are 15,328.1 and 4.52, respectively. These calculations differ from those obtained from routine Tris-glycine SDS-PAGE under reducing conditions. The calculated molecular weights are in the range calculated from Tris-tricine SDS-PAGE. The calculated isoelectric points were 4.52 and 4.58 for the 15.3 and 17.5 kD (20 and 22L kD) proteins, respectively. Original estimateε for the 20 and 22 kD proteinε (Frank et al., ibid.) were that the 20 kD protein waε acidic while the 22 kD protein was baεic. Thiε waε prior to determining the preεence of two proteinε in the 22 kD region, namely P22U and P22L. Example 13 Thiε example diεcloεeε Northern blot analyεis of D. immitiε L3 and L4 RNA using probes corresponding to a portion of p22L. D . immitiε 0-hour L3, 48-hour L3 and 6-day L4 larvae were harvested and total RNA purified therefrom as described in Example 4. Adult female poly A+ RNA was prepared similarly after the worms were ground to a fine powder in liquid nitrogen. RNA waε electrophoreεed through agaroεe-formaldehyde gels and transferred to Nytran membranes (available from Schleicher and Schuell) essentially as described by Sambrook et al., iJid. with minor modifications as described in Fourney et al., 1988, Focuε 10, 5-6. Samples of about 10 micrograms of larval total RNAs and about 1.8 μg adult female poly A+ RNA were analyzed. An initial hybridization procedure resulted in excessive non-specific binding of probe which had to be stripped by standard techniques. RNA species immobilized on the membrane were then hybridized for about 52 hours using standard Northern blot conditions to about 5 x 10 5 cpm/ml labeled GRF10. GRF10 was an anti-senεe oligomeric DNA corresponding to nucleotides 5' CATAGTTCTT GGCTTAGCGC TTC 3' of the coding region of p22L (spanning about nucleotides 15 through 37 represented above) . After washing and exposure, a strong signal was seen in the 48-hr L3 lane and a weaker εignal waε seen in the 6-day L4 lane each corresponding to RNA specieε of about 720 to about 730 bases. GRF10 esεentially did not hybridize to 0-hr L3 or adult female RNA. Although only 1.8 μg of RNA was loaded in the adult female lane, presumably this contained considerably more message than the 10 μg of larval total RNA per lane due to the poly A+ selection. The finding of a relative abundance of message in 48 hr L3, lesε in 6 day L4 and none in 0 hr L3, adultε and, presumably, microfilariae, substantiateε the pulse-chase metabolic labeling patterns described by Frank et al. , ibid . and the apparent lack of these molecules while purifying the 22U kD protein from adults. Example 14 This Example demonstrates the ability of D . immitiε p22L (also denoted D . immitiε PLA2) to encode a protein that, when expressed in bacteria, selectively binds to immune serum. Furthermore, the recombinant protein can induce the production of antibodies in rabbits and dogs capable of recognizing the corresponding native and recombinant heartworm antigens. Cats have been immunized with the recombinant protein. Recombinant molecule pET19b-PLA2_, 17 , containing D . immitiε p22L nucleotides from about base 58 through about base 474 operatively linked to bacteriophage T7Iac transcription control εequenceε and to a fuεion εequence encoding a poly-hiεtidine εegment comprising 10 histidineε was produced in the following manner. An about 417- nucleotide DNA fragment containing nucleotides spanning from about 58 through about 474 of the nucleic acid sequence of the deduced coding region of p22L disclosed above, called PLA2 417 , was PCR amplified from a clone containing D. immitiε p22L uεing the primers 5' CGCGGATCCT TCCGCATCAG AATCACAAGA AG 3' (denoted 20 NH2; BamHI site underlined) and 5' CGAAGGAATG GATCCTTATA AGTTATTAAT CG 3' (denoted 20 COOH' ; BamHI site underlined). The PCR product was digested with BamHI restriction endonucleaεe, gel purified and subcloned into expression vector pET19b (available from Novagen Inc.) that had been cleaved with BamHI. The resulting recombinant molecule pETl9b-PLA2 417 was transformed into E. coli BL21(DE3)pLysS to form recombinant cell E. coli:pETl9b-PLA2 417 . E. coli BL21(DE3)pLysS includeε a bacteriophage T7 RNA polymerase gene under the control of lac transcription control sequences. Recombinant cell E. coli:pETl9b-PLA2 417 was cultured and expression induced as described in Example 5. Protein production was monitored by SDS PAGE of recombinant cell lysates, followed by Coomassie blue staining, using standard techniques. Recombinant cell E. coli:pETl9b-PLA2 417 produced a protein, denoted PHIS-PLA2 417 , that migrated with an apparent molecular weight of about 26 kD. Such a protein was not produced by cells transformed with the pET- 19b plasmid lacking a D. immitiε DNA insert. Immunoblot analysis of recombinant cell E . coli:pETl9b-PLA2 417 lysates indicated that the 26 kD protein was able to selectively bind to immune dog serum and, as such, waε capable of binding to at leaεt one component of a serum that iε capable of inhibiting D . immitiε larval development. The E. coli:pETl9b-PLA2 417 histidine fusion peptide was separated from soluble E. coli proteins by nickel chelation chromatography and an imidazole gradient. Immunoblot analysis of the total E . coli:pET19b-PLA2 4 ι 7 lysate, column eluate and column void volume indicated that the PHIS-PLA2 417 26 kD protein can be isolated on the nickel column and was able to selectively bind to immune dog serum, and as such, was capable of binding to at least one component of a serum that is capable of inhibiting D . immitiε larval development. The column eluate was not detected by preimmune sera from the same immune dog. A rabbit was immunized twice with PHIS-PLA2 17 that was purified by chelation chromatography followed by C4 reverse phase chromatography. Antisera collected from this rabbit, denoted anti-PHIS-PLA2 4 ι 7 antiεera, waε uεed to characterize the protein in the larvae. Immunoblot analysiε was performed on 1500 microfilaria, 150 each of 7 day moεquito derived L2 from malpighian tubules, 10 day mosquito derived L3 from heads, 15 day mosquito derived L3 from heads, 0 hr in vitro cultured L3 harvested at 25°C, 0 hr in vitro cultured L3 harvested at 37°C, 48 hr in vitro cultured L3, 6 day in vitro cultured L4, 10 day in vitro cultured L4, 13 day in vitro cultured L4, 3 μg adult male antigen and 3 μg adult female antigen. Immunoreactivity to D. immitiε PLA2 (as detected using anti-PHIS-PLA2 417 antisera) was found in all L3 and L4 samples examined, but was not detected in microfilaria, L2 or adult maleε or females. Procesεing from the 22 kD form to the 20.5 kD form waε also obεerved. The 22 kD form appeared in the L3 aε early as 10 days in the mosguito, and remained aε εuch until harveεted for in vitro culture at day 15 in the moεguito. The 20 kD form waε found as early as 48 hours after removal from the mosguito. Upon εubεequent in vitro incubation, the 22 kD form gradually diminished until it was barely evident by 13 days in culture, while the 20.5 kD form was still clearly evident. Immunoblot analysis, using anti-PHIS-PLA2 4 -* 7 antisera, was performed on both P22L and P20.5 purified from D . immitiε larval excretory-secretory products demonstrating both were immunologically recognized. Two dogs were immunized three times with PHIS-PLA2 417 that was purified by chelation chromatography. Antisera collected from the dogs recognized both the P22L and P20.5 in 48 hr L3 D . immitiε . Fifteen cats were immunized twice with PHIS-PLA2 417 that was purified by chelation chromatography. These cats were challenged with 40 L3 each and are under evaluation for protection. Example 15 This example demonstrateε the production of a P22L protein (alεo referred to as PLA2) in eukaryotic cells as well as the production of a recombinant virus particle vaccine capable of expressing P22L, the P22L being capable of selectively binding to immune serum. A PCR product of about 475 nucleotides containing p22L sequences from nucleotide about 1 to about 475 (based on the p22L coding sequence discloεed above) waε generated from a p22L-containing clone of Example 12 using primers 76-40.B (5' GCGGGATCCA ACATGAACAA ACTTTTCATA GTTC3') and 20COOH (5' CGAAGGAATG GATCCTTATA AGTTATTAAT CG3') , each of which have BamHI sites (underlined) incorporated into the primerε. The BamHI-digeεted p22L 475 PCR product was subcloned into a BamHI-digested, CIP treated pSP64 vector (available from Promega) to form the vector p76-52.H3. Proper insert orientation was verified. For subcloning into the baculovirus εhuttle plasmid, BlueBacIII (available from Invitrogen), the p76-52.H3 plasmid DNA was digested with BamHI and the p22L^ insert DNA was subcloned into the unique BamHI site of BlueBacIII. The resulting recombinant molecule is denoted p76-79-A6. Insert orientation was verified and p76-79-A6 plasmid DNA waε cotranεfected into Sf9 host cells (donated by the Colorado Bioprocessing Center, Fort Collins, CO) with linear Baculogold baculovirus DNA (available from Pharmingen) and insectin cationic liposomes (available from Invitrogen) to form S . frugiperda:p76-79-A6. The resulting recombinant p22L 4 τ 5 /baculovirus iε denoted 89-11. Weεtern blots using rabbit anti-PHIS-PLA2 417 antisera produced as described in Example 14 demonstrated that inεect cellε transfected with recombinant baculovirus 89-11 expreεεed and proceεεed the protein encoded by p22l , 7 __ , namely P22L 475 , also referred to as PLA2 475 . Both the 22 and 20.5 kD forms of the protein were identified in whole cell lysateε, but only the 20.5 kD form waε εecreted into the cell culture medium. Thiε result indicated that the secretory signal of D. immitiε P22L is recognized by insect cells and that the molecule is processed naturally in this syεtem. For subcloning into the Sindbis virus shuttle plasmid, Toto2Jl (described in Example 11), p76-52.H3 DNA was digested with BamHI to release the p22L 475 insert DNA which was subcloned into the unique BamHI site of pSP64-XhoI vector, produced as described in Example 11. Proper 5' to 3' orientation of the insert within the vector was verified. The recombinant molecule is referred to as p76-79.C2. The p76-79.C2 DNA was digested with XJal and Xhol to release the P22 475 insert which was directionally subcloned into the XJal-XhoI sites of the Sindbis viruε shuttle plasmid, Toto2Jl as described in Example 11. The resulting recombinant molecule is referred to as p88-36.1B. Recombinant molecule p88-36.1B was linearized at a unique Mlul εite. Infectiouε recombinant Sindbiε tranεcriptε generated with SP6 RNA Polymeraεe and used to infect BHK (baby hamster kidney) host cells as described in Example 11 to produce BHK:p88-36.IB. The recombinant virus particle (termed 48-87) was cultivated for increaεed production. Western blot analysis of infected cell lysateε using rabbit anti-PHIS-PLA2 417 antisera produced as described in Example 14 shows that mammalian cells transfected with recombinant Sindbis virus particle 48-87 expressed, but apparently does not process, the protein encoded by p22L 475 , namely P221- 475 , also referred to as PLA2 475 . Example 16 This Example shows that P22U, but apparently not P22L or P20.5, is expreεsed in adult heartworms. Twenty-eight adult female D . immitis that had been stored at -70"C were washed 3 times with PBS, comminuted and homogenized with a glass/teflon homogenizer in 40 mM NaCl, 7.5 mM potassium phosphate pH 6.0, 1 mM EDTA, 1 mM PMSF, 2 mM DTT, 80 μg/ml leupeptin, 80 μg/mi pepstatin and 1 mg/ml TAME. The homogenate was sonicated for a total of 1 min using a 418 probe attached to a W-380.sonicator (available from Heat System-Ultraεonics, Inc., Farmington, New York), centrifuged at 5,000 g for 10 min and the supernatant was collected. Twenty four adult male D . immitiε that had been stored at -70°C were washed 3 times with TBS (50 mM Tris, 150 mM NaCl pH 8.0), frozen in liquid nitrogen and ground to a fine powder with a mortar and pestle. This powder was homogenized in 40 mm NaCl, 20 mm Tris pH 7.2, 1 mM EDTA, 1 mM PMSF, 5 μg/ml leupeptin, 5 μg/ml pepstatin and 1 mg/ml TAME. The homogenate was centrifuged at 10,000 g for 20 min and the supernatant was collected. The resultant supernatant materials of both male and female worms were further concentrated and the buffer was exchanged to 20 mM Tris, 1 mM EDTA ph 7.2 using Centriprep- 10 and Centricon-10 (available from Amicon) . All steps described were conducted at 4°C or on ice. Similar purification procedures as deεcribed for larval ES to prepare proteinε for trypsin digestion (e.g., cation exchange followed by reverse phaεe chromatography as described in Example 3) were conducted on both adult male and female somatic soluble extracts to determine if P22U, P22L or P20.5 could be found in adult heartworms. A protein conεiεtent with the P22U protein waε found following C 4 reverse phase chromatography, but neither P22L or P20.5 was seen in the eluates. The eluted protein waε subjected to trypsin digestion and the fragments separated as described in Example 3. Tryptic fragment maps of P22U from larval ES, adult female and adult male sources were virtually identical as were the N-terminal sequences of selected tryptic fragments eluting at the same position. It appears, therefore, that P22U is also found in adult D . immitiε , while there is no clear evidence to suggest the presence of either P22L or P20.5 in adult somatic soluble preparations. Example 17 Recombinant or native larval peptides are used to immunize dogs for the purpose of obtaining specifically reactive blood componentε. Recombinant antigens are administered to dogs with or without adjuvant by the subcutaneous, intramuscular, intradermal or intravenous routes. Following single or multiple immunization, blood is collected from dogs by routine venipuncture. Serum iε collected from coagulated blood and uεed directly or εtored frozen prior to uεe. Leukocyteε are collected from anticoagulant-treated blood by denεity gradient centrifugation and uεed directly or stored by freezing at l°C/minute with storage in liquid nitrogen. SEQUENCE LISTING The following Seguence Listing is submitted pursuant to 37 CFR Si.821. A copy in computer readable form is also submitted herewith. The paper and computer readable forms of this Seguence Listing are the same. (1) GENERAL INFORMATION: (i) APPLICANT: Tripp, Cynthia A. Frank, Glenn R. Grieve, Robert B. (ii) TITLE OF INVENTION: NOVEL PARASITIC HELMINTH PROTEINS (iii) NUMBER OF SEQUENCES: 4 (iv) CORRESPONDENCE ADDRESS: (A) ADDRESSEE: Sheridan Ross & Mclntosh (B) STREET: 1700 Lincoln Street, #3500 (C) CITΪ: Denver (D) STATE: CO (E) COUNTRY: U.S.A. (F) ZIP: 80203 (v) COMPUTER READABLE FORM: (A) MEDIUM TYPE: Floppy disk (B) COMPUTER: IBM PC compatible (C) OPERATING SYSTEM: PC-DOS/MS-DOS (D) SOFTWARE: Patentln Release #1.0, Version #1.25 (vi) CURRENT APPLICATION DATA: (A) APPLICATION NUMBER: US not yet assigned (B) FILING DATE: 19-AUG-1993 (C) CLASSIFICATION: (vii) PRIOR APPLICATION DATA: (A) APPLICATION NUMBER: US 08/003,257 (B) FILING DATE: 12-JAN-1993 (vii) PRIOR APPLICATION DATA: (A) APPLICATION NUMBER: US 08/003,389 (B) FILING DATE: 12-JAN-1993 (vii) PRIOR APPLICATION DATA: (A) APPLICATION NUMBER: US 07/654,226 (B) FILING DATE: 12-FEB-1991 (viii) ATTORNEY/AGENT INFORMATION: (A) NAME: Kovarik, Joseph E. (B) REGISTRATION NUMBER: 33,005 (C) REFERENCE/DOCKET NUMBER: 2618-13 (ix) TELECOMMUNICATION INFORMATION: (A) TELEPHONE: (303) 863-9700 (B) TELEFAX: (303) 863-0223 (C) TELEX: 467377 (2) INFORMATION FOR SEQ ID NO:l: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 913 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: cDNA (iii) HYPOTHETICAL: NO (iv) ANTI-SENSE: NO (vi) ORIGINAL SOURCE: (A) ORGANISM: Dirofilaria immitis (D) DEVELOPMENTAL STAGE: Larva (vii) IMMEDIATE SOURCE: (A) LIBRARY: L3 and/or L4 larval D . immitis cDNA expression library (B) CLONE: p4 (ix) FEATURE: (A) NAME/KEY: CDS (B) LOCATION: 3..911 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:l: GC GAG TTA AAT AGT CGA ATT TCC GGA GTA CAC CGT AAT ACT GCA GGT 47 Glu Leu Asn Ser Arg lie Ser Gly Val His Arg Asn Thr Ala Gly 1 5 10 15 GCT TTA CAA CGA TTT GCT CTA AAT GGT CAA AAT ACT CTT AAC GAA GGA 95 Ala Leu Gin Arg Phe Ala Leu Asn Gly Gin Asn Thr Leu Asn Glu Gly 20 25 30 TCA AGT TAT GAG CCA AAC GGA CTA TTT GTA TTT TCA GCA ATA AAC GGT 143 Ser Ser Tyr Glu Pro Asn Gly Leu Phe Val Phe Ser Ala lie Asn Gly 35 40 45 AGC CAT ACT GAT AGC TTA TCT CAG TAT GGT GAA GGA ATA AAT GAA AAT 191 Ser His Thr Asp Ser Leu Ser Gin Tyr Gly Glu Gly lie Asn Glu Asn 50 55 60 TAT CAT TCT GGA ACT AAT TAT TAT GAT GAA GTA GAA TTA AGA GAT AAA 239 Tyr His Ser Gly Thr Asn Tyr Tyr Asp Glu Val Glu Leu Arg Asp Lys 65 70 75 ACA AAT CAG ACA TCG TAC ATT AAT GGA AAT GAT AAT GGA ATC AAT GGA 287 Thr Asn Gin Thr Ser Tyr lie Asn Gly Asn Asp Asn Gly lie Asn Gly 80 85 90 95 AAG GAT GAT GAA GAT CTG GAT GAA TGC TCT GAT CAA GAA TTC CGA TGT 335 Lys Asp Asp Glu Asp Leu Asp Glu Cys Ser Asp Gin Glu Phe Arg Cys 100 105 110 CCA TAT CTA GCT AAA ACA CTT TGT GTT CAT TAT TTG AAA ATA TGC GAT 383 Pro Tyr Leu Ala Lys Thr Leu Cys Val His Tyr Leu Lys lie Cys Asp 115 120 125 GGT ATT GAT GAT TGT GGT GAT GGA AGT GAT GAA ATG AAC TGT GCT GAT 431 Gly lie Asp Asp Cys Gly Asp Gly Ser Asp Glu Met Asn Cys Ala Asp 130 135 140 GAT GAA GTG ATA ACA TCA ATA AAT GGT AAC GAA TCA ATC AAT ATC AGA 479 Asp Glu Val lie Thr Ser He Asn Gly Asn Glu Ser He Asn He Arg 145 150 155 TGT GAT CCG GAT CAA TTT CGA TGT GAA AAT GGA AAA TGT ATC GCA CAA 527 Cys Asp Pro Asp Gin Phe Arg Cys Glu Asn Gly Lys Cys He Ala Gin 160 165 170 175 ATT GAT CGA TGT AAT CGA AAA TAT GAT TGT GAT GAT GGT ACA GAT GAA 575 He Asp Arg Cys Asn Arg Lys Tyr Asp Cys Aβp Asp Gly Thr Asp Glu 180 185 190 ACA ACT TGT GAA TAT TTC GTG CAA GCT TTG CAA CAA GCG AGA GGT GTA 623 Thr Thr Cys Glu Tyr Phe Val Gin Ala Leu Gin Gin Ala Arg Gly Val 195 200 205 ACG GTG CAG GAT AAT GCA ATT CGA GAT GAC GAG ATA CCA AAT TAT ACT 671 Thr Val Gin Asp Asn Ala He Arg Asp Asp Glu He Pro Asn Tyr Thr 210 215 220 GTA TCC ATG GAA CAG AAA TAC GAT CAA GTA AAG GAA GAT AAG GAG CGG 719 Val Ser Met Glu Gin Lys Tyr Asp Gin Val Lys Glu Asp Lys Glu Arg 225 230 235 CGA ATG CAA GAG GAG GAG GAA CAG GAA AGG CTG AGA GAG TAC GAG GAA 767 Arg Met Gin Glu Glu Glu Glu Gin Glu Arg Leu Arg Glu Tyr Glu Glu 240 245 250 255 CAG ATA CAG GAA AAA TTG AGG CAG GAG GAA GAA AGA GAA CGG CAA GAA 815 Gin He Gin Glu Lys Leu Arg Gin Glu Glu Glu Arg Glu Arg Gin Glu 260 265 270 CAG GAA AGA AGA CAA AAG GAA CGA GAA AGA ATG GAA CAA GAA AGG ATA 863 Gin Glu Arg Arg Gin Lys Glu Arg Glu Arg Met Glu Gin Glu Arg He 275 280 285 AGA CAA GAA TAT GAT GAA AAG GAA AGA CAA AGG CAA TAT GCT GAA CAG 911 Arg Gin Glu Tyr Asp Glu Lys Glu Arg Gin Arg Gin Tyr Ala Glu Gin 290 295 300 GC 913 (2) INFORMATION FOR SEQ ID NO:2: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 303 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (xi) SEQUENCE DESCRIPTION: SEQ ID NO:2: Glu Leu Asn Ser Arg He Ser Gly Val His Arg Asn Thr Ala Gly Ala 1 5 10 15 Leu Gin Arg Phe Ala Leu Asn Gly Gin Asn Thr Leu Asn Glu Gly Ser 20 25 30 Ser Tyr Glu Pro Asn Gly Leu Phe Val Phe Ser Ala He Asn Gly Ser 35 40 45 His Thr Asp Ser Leu Ser Gin Tyr Gly Glu Gly He Asn Glu Asn Tyr 50 55 60 His Ser Gly Thr Asn Tyr Tyr Asp Glu Val Glu Leu Arg Asp Lys Thr 65 70 75 80 Asn Gin Thr Ser Tyr He Asn Gly Asn Asp Asn Gly He Asn Gly Lys 85 90 95 Asp Asp Glu Asp Leu Asp Glu Cys Ser Asp Gin Glu Phe Arg Cys Pro 100 105 110 Tyr Leu Ala Lys Thr Leu Cys Val His Tyr Leu Lys He Cys Asp Gly 115 120 125 He Asp Asp Cys Gly Asp Gly Ser Asp Glu Met Asn Cys Ala Asp Asp 130 135 140 Glu Val He Thr Ser He Asn Gly Asn Glu Ser He Asn He Arg Cys 145 150 155 160 Asp Pro Asp Gin Phe Arg Cys Glu Asn Gly Lys Cys He Ala Gin He 165 170 175 Asp Arg Cys Asn Arg Lys Tyr Asp Cys Asp Asp Gly Thr Asp Glu Thr 180 185 190 Thr Cys Glu Tyr Phe Val Gin Ala Leu Gin Gin Ala Arg Gly Val Thr 195 200 205 Val Gin Asp Asn Ala He Arg Asp Asp Glu He Pro Asn Tyr Thr Val 210 215 220 Ser Met Glu Gin Lys Tyr Asp Gin Val Lys Glu Asp Lys Glu Arg Arg 225 230 235 240 Met Gin Glu Glu Glu Glu Gin Glu Arg Leu Arg Glu Tyr Glu Glu Gin 245 250 255 He Gin Glu Lys Leu Arg Gin Glu Glu Glu Arg Glu Arg Gin Glu Gin 260 265 270 Glu Arg Arg Gin Lys Glu Arg Glu Arg Met Glu Gin Glu Arg He Arg 275 280 285 Gin Glu Tyr Asp Glu Lys Glu Arg Gin Arg Gin Tyr Ala Glu Gin 290 295 300 (2) INFORMATION FOR SEQ ID NO:3: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 1016 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: cDNA (iii) HYPOTHETICAL: NO (iv) ANTI-SENSE: NO (vi) ORIGINAL SOURCE: (A) ORGANISM: Dirof ilaria immitis (vii) IMMEDIATE SOURCE: (A) LIBRARY: adult female D . immitis cDNA expression library (B) CLONE: p22U (ix) FEATURE: (A) NAME/KEY: CDS (B) LOCATION: 3.-629 (ix) FEATURE: (A) NAME/KEY: 3'UTR (B) LOCATION: 630..1016 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:3: GT TTT GTT GTA CTA CTC GTT GTT GCA ATA TGG ATT GAA ATG AGC CAA 47 Phe Val Val Leu Leu Val Val Ala He Trp He Glu Met Ser Gin 1 5 10 15 GGC CAA CAA ATG ATC AAA CAA TGT AAA TGT TCT GAT ATT GCA CCA TGT 95 Gly Gin Gin Met He Lys Gin Cys Lys Cys Ser Asp He Ala Pro Cys 20 25 30 CAA TTA ACT GCC GTT CAA TCA GTT TTA CCA TGT GCT GAT CAA TGC CAG 143 Gin Leu Thr Ala Val Gin Ser Val Leu Pro Cys Ala Asp Gin Cys Gin 35 40 45 AAA TAT ATT ACT TCA ATT GGT GGT AAT TAT GAT CAA ATT AGT AAC TGT 191 Lys Tyr He Thr Ser He Gly Gly Asn Tyr Asp Gin He Ser Asn Cys 50 55 60 TTT AAA CAG AAA CAA TCA ATT ATA AAT GAT GCT ATG AAA TGT GCT CAA 239 Phe Lys Gin Lys Gin Ser He He Asn Asp Ala Met Lys Cys Ala Gin 65 70 75 GAT GCT TTC CCA AAT GCA TGC GCA CAA GGT GAA CCA AAA ATG. GTA CCA 287 Asp Ala Phe Pro Asn Ala Cys Ala Gin Gly Glu Pro Lys Met Val Pro 80 85 90 95 AAA CGA TTC GGA AAA GGT CTT CAA TTA GCT GTA ATG ACT GAT ATC AAC 335 Lys Arg Phe Gly Lys Gly Leu Gin Leu Ala Val Met Thr Asp He Asn 100 105 110 - AAA GAA TTA CAA CGA ATG GGA ATA GCA AAT CAA GTT ACT CAA CTA ATC 383 Lys Glu Leu Gin Arg Met Gly He Ala Asn Gin Val Thr Gin Leu He 115 120 125 TCC CAA GGT CGA CGA TTC TTT AAA TGC TTC CAA TCG TGT ATG ATG AAA 431 Ser Gin Gly Arg Arg Phe Phe Lys Cys Phe Gin Ser Cys Met Met Lys 130 135 140 AAA TTG GGC TCA TGT TCT CCA GAT TGT GGT CTT GAT TTA CCA TCT GAT 479 Lys Leu Gly Ser Cys Ser Pro Asp Cys Gly Leu Asp Leu Pro Ser Asp 145 150 155 AAT GTT ATG GTT CAA ACA GTT AAA AAT TGC GCT CAA AAA AGT GGT ATT 527 Asn Val Met Val Gin Thr Val Lys Asn Cys Ala Gin Lys Ser Gly He 160 165 170 175 CAA ACT GCA TCG GTG CAA GAT CTT TGC TTT TGC GTC GAA CAA GCT GGT 575 Gin Thr Ala Ser Val Gin Asp Leu Cys Phe Cys Val Glu Gin Ala Gly 180 185 190 ATT CGG CAA CTT TCT GAT GTA TGT CCT CGT ATA CAA ATT TTC AAA ACG 623 He Arg Gin Leu Ser Asp Val Cys Pro Arg He Gin He Phe Lys Thr 195 200 205 AAA TGAGTATTGA GAATATTGCA CTAGCAGCAA TCATTATTTT TCTCGAGAAT 676 Lys TTTCGCTATC AATAAGTTGG AATATGATTA CAATAATATA TATATTAACT GCAAAAATCT 736 TTCTTCTTCA AAATTATTTT TCATTTCGCT CTCATAATTG CATGATAATA GTCATAATGA 796 AAAACAGGTT TTCTTTTTTT AAAATGATAA CTTCAAACAA ATAGGTATTT CTTGATAT T 856 ATATGTATGT ATGTATGTGT GTGTGTGTGT GTGTGTGTAT GTGTGTGTTT GTGTATGTGT 916 ATATGTATGT ATGTATGTAT GTATGTATGT ATGTGTAGGA GAAAAGCAAA CTAAACAGTA 976 AATGAAAGAA AAAAATAAGT CAAATAAAAG TTTGATAATT 1016 (2) INFORMATION FOR SEQ ID NO:4: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 208 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (xi) SEQUENCE DESCRIPTION: SEQ ID NO:4: Phe Val Val Leu Leu Val Val Ala He Trp He Glu Met Ser Gin Gly 1 5 10 15 Gin Gin Met He Lys Gin Cys Lys Cys Ser Asp He Ala Pro Cys Gin 20 25 30 Leu Thr Ala Val Gin Ser Val Leu Pro Cys Ala Asp Gin Cys Gin Lys 35 40 45 Tyr He Thr Ser He Gly Gly Asn Tyr Asp Gin He Ser Asn Cys Phe 50 55 60 Lys Gin Lys Gin Ser He He Asn Asp Ala Met Lys Cys Ala Gin Asp 65 70 75 80 Ala Phe Pro Asn Ala Cys Ala Gin Gly Glu Pro Lys Met Val Pro Lys 85 90 95 Arg Phe Gly Lys Gly Leu Gin Leu Ala Val Met Thr Asp He Asn Lys 100 105 110 Glu Leu Gin Arg Met Gly He Ala Asn Gin Val Thr Gin Leu He Ser 115 120 125 Gin Gly Arg Arg Phe Phe Lys Cys Phe Gin Ser Cys Met Met Lys Lys 130 135 140 Leu Gly Ser Cys Ser Pro Asp Cys Gly Leu Asp Leu Pro Ser Asp Asn 145 150 155 160 Val Met Val Gin Thr Val Lys Asn Cys Ala Gin Lys Ser Gly He Gin 165 170 175 Thr Ala Ser Val Gin Asp Leu Cys Phe Cys Val Glu Gin Ala Gly He 180 185 190 Arg Gin Leu Ser Asp Val Cys Pro Arg He Gin He Phe Lys Thr Lys 195 200 205 While variouε embodimentε of the preεent invention have been deεcribed in detail, it iε apparent that modifications and adaptations of those embodiments will occur to those skilled in the art. It is to be expressly understood, however, that such modifications and adaptations are within the scope of the present invention, as set forth in the following claims:

Claims: What iε claimed iε: 1. An isolated parasitic helminth nucleic acid sequence capable of hybridizing, under stringent conditions, to at leaεt a portion of at leaεt one Dirofilaria immitiε (D . immitis) nucleic acid εequence selected from the group consisting of D. immitiε nucleic acid sequence p4 and D. immitis nucleic acid sequence p22U. 2. The isolated nucleic acid sequence of Claim 1, wherein said isolated nucleic acid sequence encodes a protein capable of selectively binding to at least one component of immune serum, said immune εerum being capable of inhibiting helminth development. 3. The iεolated nucleic acid seguence of Claim 2, wherein said immune serum is derived from an animal that is essentially immune to infection by said helminth. 4. The iεolated nucleic acid εequence of Claim 2, wherein εaid immune εerum is derived from an animal immunized with a composition comprising paraεitic helminth larvae selected from the group consisting of third stage larvae, fourth stage larvae, and mixtures thereof. 5. The isolated nucleic acid sequence of Claim 1, wherein said parasitic helminth iε εelected from the group conεiεting of nematodes, cestodeε and trematodes. 6. The iεolated nucleic acid εequence of Claim 1, wherein εaid parasitic helminth comprises a nematode selected from the group consiεting of filarial, ascarid, strongyle and trichostrongyle nematodeε. 7. The isolated nucleic acid sequence of Claim 1, wherein said parasitic helminth is selected from the group consisting of Dirofilaria , Onchocerca , Brugia , Wuchereria, Loa, Acanthocheilonema , Dipetalonema , Setaria , Paraf ilaria and Stephanof ilaria filarial nematodes. 8. The isolated nucleic acid sequence of Claim 1, wherein said parasitic helminth compriseε a D. immitis nematode. 9. The iεolated nucleic acid εequence of Claim 1, wherein said D . immitiε nucleic acid sequence is selected from the group conεiεting of D . immitiε nucleic acid εequence p4, a nucleic acid εequence including D . immitis p4, a nucleic acid sequence comprising a fragment of D . immitis p4, D . immitiε nucleic acid sequence p22U, a nucleic acid sequence including D. immitiε p22U and a nucleic acid sequence comprising a fragment of D. immitiε p22U. 10. The isolated nucleic acid seguence of Claim 1, wherein said D. immitiε nucleic acid sequence is selected from the group conεiεting of SEQ ID N0:1, or a functional equivalent thereof, a nucleic acid εequence containing at least a portion of SEQ ID N0:1 or a functional eguivalent thereof, a fragment of SEQ ID N0:l or a functional equivalent thereof, SEQ ID NO:3 or a functional equivalent thereof, a nucleic acid sequence containing at least a portion of SEQ ID NO:3 or a functional equivalent thereof, and a fragment of SEQ ID NO:3 or a functional equivalent thereof. 11. The isolated nucleic acid sequence of Claim 1, wherein said isolated nucleic acid εequence compriεes an oligonucleotide capable of hybridizing to said D . immitiε nucleic acid seguence under stringent hybridization conditions. 12. The isolated nucleic acid sequence of Claim 1, wherein said isolated nucleic acid sequence, when administered to an animal in an effective manner, is capable of protecting said animal from infection by εaid helminth. 13. The iεolated nucleic acid εeguence of Claim 1, wherein εaid isolated nucleic acid seguence encodes a protein that, when administered to an animal in an effective manner, iε capable of protecting εaid animal from infection by said helminth. 14. The isolated nucleic acid sequence of Claim 1, wherein said isolated nucleic acid sequence is obtained by a method comprising: (a) culturing a parasitic helminth expreεsion library under conditions that promote production of proteins encoded by said library; (b) contacting said library with εaid immune εerum under selective binding conditions; and (c) selecting a colony or phage plaque that contains a nucleic acid sequence encoding a protein capable of selectively binding to said immune serum. 15. A recombinant molecule compriεing at leaεt one iεolated nucleic acid sequence set forth in Claim 1 operatively linked to at least one transcription control sequence. 16. A recombinant cell compriεing a cell tranεformed with at leaεt one iεolated nucleic acid sequence set forth in Claim 1 operatively linked to at least one transcription control sequence. 17. A recombinant cell comprising a cell transformed with at least one isolated nucleic acid sequence set forth in Claim 1 in a manner such that said recombinant cell is capable of expressing said isolated nucleic acid sequence. 18. An isolated parasitic helminth protein, or mimetope thereof, capable of selectively binding to at least one component of immune serum that is capable of inhibiting helminth development, said protein being encoded by a parasitic helminth nucleic acid εequence capable of hybridizing, under stringent conditions, to at leaεt a portion of at least one D . immitiε nucleic acid sequence selected from the group consisting of D . immitiε nucleic acid sequence p4 and D . immitiε nucleic acid sequence p22U. 19. The protein of Claim 18, wherein said immune serum is derived from an animal that is essentially immune to infection by said helminth. 20. The protein of Claim 18, wherein said immune serum is derived from an animal immunized with a compoεition comprising parasitic helminth larvae selected from the group conεisting of third stage larvae, fourth stage larvae, and mixtures thereof. 21. The protein of Claim 18, wherein εaid paraεitic helminth nucleic acid sequence is selected from the group consisting of D . immitis nucleic acid sequence p4, a nucleic acid sequence including D . immitiε p4, a nucleic acid sequence comprising a fragment of D. immitiε p4, D. immitis nucleic acid sequence p22U, a nucleic acid sequence including D . immitis p22U, and a nucleic acid sequence comprising a fragment of D . immitiε p22U. 22. The protein of Claim 18, wherein said protein is encoded by a parasitic helminth nucleic acid εequence selected from the group consiεting of SEQ ID N0:1, or a functional equivalent thereof, a nucleic acid sequence containing at least a portion of SEQ ID N0:1 or a functional equivalent thereof, a fragment of SEQ ID N0:l or a functional equivalent thereof, SEQ ID NO:3 or a functional equivalent thereof, a nucleic acid sequence containing at least a portion of SEQ ID NO:3 or a functional equivalent thereof, and a fragment of SEQ ID NO:3 or a functional equivalent thereof. 23. The protein of Claim 18, wherein said protein comprises at least a portion of an amino acid εequence εelected from the group conεisting of SEQ ID NO:2 or functional equivalent thereof and SEQ ID NO:4 or functional equivalent thereof. 24. The protein of Claim 18, wherein said protein being encoded by a paraεitic helminth nucleic acid sequence capable of hybridizing, under stringent conditions, to at least a portion of D . immitiε nucleic acid seguence p4 comprises a parasitic helminth LDL receptor-related protein class A cysteine-rich motif. 25. The protein of Claim 24, wherein said motif comprises DDCGDGSDE. 26. The protein of Claim 18, wherein said protein or mimetope thereof, when administered to an animal in an effective manner, is capable of protecting said animal from infection by said helminth. 27. The protein of Claim 18, wherein said protein or mimetope thereof is capable of protecting an animal from heartworm infection. 28. An isolated antibody capable of selectively binding to a parasitic helminth protein or mimetope thereof, said antibody being produced by a method comprising administering to an animal an effective amount of an isolated protein or mimetope thereof to produce said antibody, said protein being capable of selectively binding to at least one component of immune serum that is capable of inhibiting helminth development, and said protein being encoded by a parasitic helminth nucleic acid sequence capable of hybridizing, under stringent conditions, to at least a portion of at least one D . immitiε nucleic acid seguence selected from the group consiεting of D . immitiε nucleic acid sequence p4 and D . immitis nucleic acid εequence p22U. 29. The antibody of Claim 28, wherein εaid antibody, when adminiεtered to an animal in an effective manner, iε capable of protecting said animal from infection by said helminth. 30. A therapeutic composition capable of protecting an animal from parasitic helminth infection when administered to said animal in an effective manner, said composition comprising at least one protective compound selected from the group consisting of an isolated nucleic acid seguence capable of hybridizing, under stringent conditions, to at least a portion of at least one D . immitis nucleic acid sequence selected from the group consisting of D . immitiε nucleic acid seguence p4 and D . immitiε nucleic acid sequence p22U; an iεolated protein, or mimetope thereof, capable of εelectively binding to at leaεt one component of immune εerum capable of inhibiting helminth development, εaid protein being encoded by εaid isolated nucleic acid sequence; and an antibody capable of selectively binding to a parasitic helminth protein or mimetope thereof, said antibody being produced by a method comprising administering to an animal an effective amount of said isolated protein or mimetope thereof to produce said antibody. 31. The composition of Claim 30, wherein said composition further comprises at least one component selected from the group consisting of an excipient, an adjuvant and a carrier. 32. The composition of Claim 30, wherein said compoεition comprises at least one of said protein or mimetope thereof and at least one Dirofilaria protein or functional equivalent thereof, said Dirofilaria protein being selected from the group consisting of P39, P22L, P20.5, Di22, and larval proteases. 33. The composition of Claim 30, wherein said antibody further comprises a cytotoxic agent conjugated to said antibody. 34. The composition of Claim 30, wherein said isolated nucleic acid seguence is delivered to said cell by direct injection of said isolated nucleic acid sequence or by a vehicle selected from the group consisting of recombinant virus particle vaccines and recombinant cell vaccines. 35. A method to protect an animal from infection by a parasitic helminth comprising administering to said animal in an effective manner a therapeutic composition comprising at least one protective compound selected from the group consiεting of an isolated nucleic acid seguence capable of hybridizing, under stringent conditions, to at least a portion of at least one D . immitiε nucleic acid sequence selected from the group consisting of D . immitiε nucleic acid sequence p4 and D . immitiε nucleic acid sequence p22U; an isolated protein, or mimetope thereof, capable of selectively binding to at least one component of immune εerum capable of inhibiting helminth development, εaid protein being encoded by εaid iεolated nucleic acid seguence; and an antibody capable of selectively binding to a parasitic helminth protein or mimetope thereof, said antibody being produced by a method comprising administering to an animal an effective amount of said isolated protein or mimetope thereof to produce said antibody. 36. The method of Claim 35, wherein said composition comprises a recombinant viruε particle vaccine or a recombinant cell vaccine. 37. A method to produce an isolated parasitic helminth protein comprising culturing in an effective medium a cell capable of expressing said protein, said protein being encoded by a parasitic helminth nucleic acid sequence capable of hybridizing, under stringent conditions, to at least a portion of at least one D . immitiε nucleic acid sequence selected from the group consisting of D. immitiε nucleic acid sequence p4 and D . immitiε nucleic acid sequence p22U. 38. A method to produce an antibody capable of selectively binding to a protein or mimetope thereof, said method comprising administering to an animal an effective amount of an isolated protein or mimetope thereof to produce said antibody, wherein said protein is capable of selectively binding to at least one component of immune serum that is capable of inhibiting helminth development, and wherein said protein is encoded by an isolated parasitic helminth nucleic acid sequence capable of hybridizing, under stringent conditions, to at least a portion of at least one D . immitiε nucleic acid sequence selected from the group consiεting of D. immitiε nucleic acid sequence p4 and D . immitiε nucleic acid sequence p22U. 39. A therapeutic composition capable of protecting an animal from paraεitic helminth infection when administered to said animal in an effective manner, said composition comprising a compound capable of substantially interfering with the function of a parasitic helminth LDL receptor-related protein clasε A cyεteine-rich motif. 40. The compoεition of Claim 39, wherein εaid function comprises sterol uptake. 41. The composition of Claim 39, wherein said therapeutic composition comprises a protein encoded by an isolated nucleic acid seguence capable of hybridizing, under stringent conditions, to at least a portion of D . immitiε nucleic acid sequence p4. 42. A method to protect animals from paraεitic helminth infection comprising administering to said animal in an effective manner the therapeutic composition set forth in Claim 39. 43. A biologically pure protein which is iεolatable from the L3 or L4 larval stage of a nematode parasitic in mammals, or a fragment of said protein, wherein said protein or fragment thereof is immunoreactive with a component validated as protective in an immune host, and wherein said protein is selected from the group consisting of a P39 protein having a molecular weight of about 39 kD as measured by Tris-glycine SDS-PAGE, a P22L protein having a molecular weight of about 22 kD as measured by Tris- glycine SDS-PAGE and a molecular weight of about 19 kD measured by Tris-tricine SDS-PAGE, and a P20.5 protein having a molecular weight of about 20.5 kD as measured by Tris-glycine SDS-PAGE and a molecular weight of about 16 kD as measured by Tris-tricine SDS-PAGE. 44. The protein of Claim 43, wherein said nematode is a filarial nematode. 45. The protein of Claim 44, wherein said nematode is D. immitiε . 46. The protein of Claim 43, wherein said protein is selected from the group consisting of a protein comprising the amino acid sequence MIDLKKIVDD EYNIDVKPDK NGIEEKKVIE LETQNVRNDV DKIDSDDDDF PEYEIPAGEL ILKKEENDEE YRCVEIPYYI RDCIELLNEQ NDCAKFEAAF NALKPMIRRR AVGYEQSAEE LLCRLIDLSD RFKIEHFQEK RLQLIESCLV TSPYLGNVAI DVMFSRKCSM MNRYIVLKAL SDAASEYSSP AGIVENPAIE IPKNGGDVEG HVSLCDGDGK LISKTKLFVR APITMLKENR FTPIANSFFY PLTAIDQHRE HLDLIGRDSE LLSKILFCMA HLIKCSGTSP CTLRMCRYVD or an allelic variant or fragment thereof, a protein comprising the amino acid sequence MNKLFIVLGL ALLFVALPSA SESQEETVSF EESDEDYEDD SEDQTKEEEH SKEEDRSEEH DDHSAEDDKF VTKGKFVESD GKMKHCKTHE ACYDQREPQS WCILKPHQSW TQRGCFCESK KHACVIERKS GDKLEYSYCS PRKNWQCSYD or an allelic variant or fragment thereof, and a protein comprising the amino acid seguence ESQEETVSF EESDEDYEDD SEDQTKEEEH SKEEDRSEEH DDHSAEDDKF VTKGKFVESD GKMKHCKTHE ACYDQREPQS WCILKPHQSW TQRGCFCESK KHACVIERKS GDKLEYSYCS PRKNWQCSYD or an allelic variant or fragment thereof. 47. An isolated nucleic acid εeguence which encodes the protein or fragment of Claim 43. 48. The nucleic acid sequence of Claim 47, wherein said nucleic acid sequence is εelected from a nucleic acid which includeε the εequence ATGAT AGATTTGAAG AAGATTGTGG ATGATGAATA TAACATTGAT GTGAAGCCTG ATAAAAATGG CATTGAAGAG AAGAAAGTGA TAGAACTGGA AACGCAGAAT GTGCGGAATG ATGTAGATAA AATTGATAGC GATGATGATG ACTTCCCTGA ATATGAAATT CCTGCAGGAG AATTGATTCT GAAAAAGGAA GAAAATGATG AAGAATATCG CTGTGTAGAA ATCCCATATT ATATTAGGGA TTGTATTGAG TTGCTCAATG AGCAGAATGA TTGTGCCAAA TTTGAGGCTG CATTCAATGC TCTGAAACCA ATGATTAGAC GACGAGCTGT TGGTTATGAA CAATCCGCGG AAGAACTACT CTGCCGACTT ATTGATCTTA GTGATCGCTT CAAAATTGAA CATTTCCAGG AGAAGCGACT ACAGCTTATT GAATCATGTC TAGTGACGAG TCCTTATCTG GGAAATGTAG CTATTGATGT CATGTTTTCG AGAAAATGTT CAATGATGAA TAGATATATC GTTTTAAAGG CTCTATCAGA TGCGGCGTCA GAATATTCAT CTCCAGCCGG AATTGTCGAA AATCCAGCCA TCGAAATTCC AAAAAACGGA GGTGATGTTG AAGGGCATGT CTCTCTCTGC GATGGCGATG GAAAACTGAT CTCCAAGACA AAACTTTTCG TGAGAGCACC AATTACGATG TTAAAGGAAA ACAGATTTAC ACCAATAGCA AATTCCTTCT TCTATCCCTT GACTGCAATC GATCAGCATC GTGAACATCT TGATCTCATT GGGAGAGATT CGGAATTACT GAGTAAGATT CTTTTCTGTA TGGCTCATTT GATCAAATGT TCTGGCACTT CTCCATGTAC GCTTAGAATG TGTAGGTATG TTGACTGA or an allelic variant or fragment thereof, a nucleic acid which includeε the sequence ATGAACAAAC TTTTCATAGT TCTTGGCTTA GCGCTTCTTT TTGTTGCATT ACCTTCCGCA TCAGAATCAC AAGAAGAGAC TGTATCTTTT GAAGAAAGCG ACGAAGATTA TGAAGACGAT AGTGAAGATC AAACAAAAGA AGAGGAACAT TCAAAAGAGG AAGATCGTTC AGAAGAACAC GACGATCATT CAGCTGAAGA CGATAAATTT GTAACTAAAG GAAAATTTGT TGAAAGTGAC GGCAAGATGA AGCATTGCAA AACCCATGAA GCTTGCTATG ATCAACGTGA ACCACAATCG TGGTGCATAT TAAAACCGCA TCAGTCATGG ACACAAAGAG GTTGTTTCTG CGAATCAAAA AAACATGCAT GCGTTATCGA ACGAAAAAGC GGCGACAAAT TGGAATATTC GTATTGCTCA CCCCGAAAAA ACTGGCAGTG TTCATACGAT TAA or an allelic variant or fragment thereof, and a nucleic acid which includes the sequence GAATCAC AAGAAGAGAC TGTATCTTTT GAAGAAAGCG ACGAAGATTA TGAAGACGAT AGTGAAGATC AAACAAAAGA AGAGGAACAT TCAAAAGAGG AAGATCGTTC AGAAGAACAC GACGATCATT CAGCTGAAGA CGATAAATTT GTAACTAAAG GAAAATTTGT TGAAAGTGAC GGCAAGATGA AGCATTGCAA AACCCATGAA GCTTGCTATG ATCAACGTGA ACCACAATCG TGGTGCATAT TAAAACCGCA TCAGTCATGG ACACAAAGAG GTTGTTTCTG CGAATCAAAA AAACATGCAT GCGTTATCGA ACGAAAAAGC GGCGACAAAT TGGAATATTC GTATTGCTCA CCCCGAAAAA ACTGGCAGTG TTCATACGAT TAA or an allelic variant or fragment thereof. 49. An oligonucleotide which is the complement of the nucleic acid of Claim 48 or of a portion thereof. 50. An oligonucleotide capable of forming a triplex with a double-stranded DNA comprising the nucleic acid sequence of Claim 48 and its complement. 51. An oligonucleotide which is the complement to at least a portion of an mRNA encoding the protein of Claim 43, or of the sense strand of the DNA region which effects production of said protein. 52. An oligonucleotide capable of forming a triplex with a double-stranded DNA comprising the DNA region which effects expreεεion of the protein of Claim 43. 53. A recombinant vector compriεing at least a portion of a nucleic acid seguence of Claim 48. 54. A recombinant expression system capable of producing the protein of Claim 43 which comprises a nucleic acid sequence encoding said protein operably linked to at least one control sequence. 55. The expression system of Claim 54, wherein εaid protein comprises a protein of Claim 46. 56. A recombinant host cell which contains the expression system of Claim 54. 57. A method to produce a protein which is isolatable from the L3 or L4 larval stage of a nematode parasitic in mammals, or a fragment of said protein, wherein said protein or fragment thereof is immunoreactive with a component validated as protective in an immune host and wherein said protein is selected from the group consiεting of a P39 protein having a molecular weight of 39 kD measured by Tris-glycine SDS-PAGE, a P22L protein having a molecular weight of 22 kD measured by Tris-glycine SDS-PAGE and a molecular weight of about 19 kD measured by Tris- tricine SDS-PAGE, and a P20.5 protein having a molecular weight of 20.5 kD measured by Tris-glycine SDS-PAGE and a molecular weight of about 16 kD measured by Triε-tricine SDS-PAGE, said method comprising: (a) culturing the cells of Claim 56 under conditions compatible with expression; and (b) recovering said protein or fragment from the culture. 58. A recombinant protein or fragment prepared by the method of Claim 57. 59. A pharmaceutical composition uεeful for immunizing a susceptible mammalian host against a parasitic nematode, said composition comprising said protein or fragment of Claim 43 in admixture with a suitable pharmaceutically acceptable excipient. 60. A method to immunize a mammalian host against a parasitic nematode, said method comprising administering to said host an effective amount of said protein or fragment of Claim 43 or a pharmaceutical composition thereof. 61. The method of Claim 60 wherein said protein is isolatable from a filarial nematode. 62. The method of Claim 60 wherein said protein is isolatable from D. immitiε and wherein said host is canine. 63. A pharmaceutical composition for use in immunizing a mammalian host against a parasitic nematode, wherein said composition comprises the expression system of Claim 54 in admixture with a pharmaceutically acceptable excipient. 64. A method to immunize a mammalian host againεt a paraεitic nematode, said method compriεing administering to said host an effective amount of the expression system of claim 54, or a pharmaceutical composition thereof. 65. The method of claim 64, wherein said protein is isolatable from a filarial nematode. 66. The method of claim 64, wherein said protein iε isolatable from D. immitiε and wherein εaid host is canine. 67. A method to interrupt the life cycle of a nematode parasitic in mammals, said method comprising contacting said nematode with said oligonucleotide of Claim 49, 30, 51 or 52. 68. The method of Claim 67, wherein said contacting is conducted by administering said oligonucleotide to a host infected by said nematode. 69. A composition of antibodies consisting essentially of antibodies immunoreactive with the protein of Claim 43. 70. The composition of claim 69, wherein said antibodies are monoclonal antibodies.

Inventors: FRANK GLENN R, GRIEVE ROBERT B, MIKA-GRIEVE MARCIA, TRIPP CYNTHIA ANN, FRANK, GLENN, R., GRIEVE, ROBERT, B., MIKA-GRIEVE, MARCIA, TRIPP, CYNTHIA, ANN
Applicants: FRANK GLENN R, GRIEVE ROBERT B, MIKA GRIEVE MARCIA, PARAVAX INC, TRIPP CYNTHIA ANN, UNIV COLORADO RES, COLORADO STATE UNIVERSITY RESEARCH FOUNDATION, FRANK, GLENN, R., GRIEVE, ROBERT, B., MIKA-GRIEVE, MARCIA, PARAVAX, INC., TRIPP, CYNTHIA, ANN
Application year: 1994
Main classification: A61K31
IPC codes: A61K31, A61K35, A61K38, A61K39, A61P33, C07H21, C07K14, C07K16, C12N5, C12N15, C12P21, C12R1, G01N33